Imaging element, imaging method and electronic apparatus

ABSTRACT

There is provided an imaging device including a pixel array section including pixel units two-dimensionally arranged in a matrix pattern, each pixel unit including a photoelectric converter, and a plurality of column signal lines disposed according to a first column of the pixel units. The imaging device further includes an analog to digital converter that is shared by the plurality of column signal lines.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.17/948,908, filed Sep. 20, 2022, which is a continuation of U.S. patentapplication Ser. No. 17/119,084, filed Dec. 11, 2020, now U.S. Pat. No.11,483,509, which is a continuation of U.S. patent application Ser. No.16/840,077, filed Apr. 3, 2020, now U.S. Pat. No. 10,911,707, which is acontinuation of U.S. patent application Ser. No. 16/559,795, filed Sep.4, 2019, now U.S. Pat. No. 10,659,716, which is a continuation of U.S.patent application Ser. No. 15/987,363, filed May 23, 2018, now U.S.Pat. No. 10,432,884, which is a continuation of U.S. patent applicationSer. No. 15/313,645, filed Nov. 23, 2016, now U.S. Pat. No. 10,021,335,which is a national stage application under 35 U.S.C. 371 and claims thebenefit of PCT Application No. PCT/JP2015/002549, having aninternational filing date of 21 May 2015, which designated the UnitedStates, which PCT application claims the benefit of Japanese PriorityPatent Application JP 2014-114143, filed Jun. 2, 2014; Japanese PriorityPatent Application JP 2014-230001, filed Nov. 12, 2014; JapanesePriority Patent Application JP 2014-230002, filed Nov. 12, 2014; and,Japanese Priority Patent Application JP 2014-230000, filed Nov. 12,2014, the entire contents of each of which are incorporated herein byreference in their entirety.

TECHNICAL FIELD

The present disclosure relates to an imaging element, an imaging method,and an electronic apparatus, and particularly to an imaging element, animaging method, and an electronic apparatus that can attain a speedincrease using a low-power consumption.

BACKGROUND ART

In the related art, an electronic apparatus having an imaging function,such as a digital still camera or a digital video camera, uses asolid-state imaging element, such as a charge coupled device (CCD) imagesensor or a complementary metal oxide semiconductor (CMOS) image sensor.The solid-state imaging element includes a pixel, in which a photodiode(PD) that performs a photoelectric conversion and a plurality oftransistors are combined, and an image is formed based on an imagesignal that is output from a plurality of pixels that are disposed in aflat manner. In addition, for example, the image signals that are outputfrom the pixels are converted in parallel into digital signals fromanalog signals by a plurality of analog to digital (AD) convertersdisposed in each pixel column.

For such a solid-state imaging element, the present applicant proposes asolid-state imaging element that can increase a speed of AD conversionprocessing by performing count processing in a down-count mode and anup-count mode in an AD converter (for example, refer to PTL 1).

In addition, the present applicant proposes a solid-state imagingelement that can reduce noise by performing AD conversion of a pixelsignal of a reset level and a pixel signal of a signal level byrepetition for multiple times (for example, refer to PTL 2).

CITATION LIST Patent Literature

-   [PTL 1]-   Japanese Unexamined Patent Application Publication No. 2005-303648-   [PTL 2]-   Japanese Unexamined Patent Application Publication No. 2009-296423

SUMMARY Technical Problem

However, in the related art, it is necessary to read a pixel signal at ahigh speed from a solid-state imaging element. In addition, in recentyears, applications that are used for a small terminal, such as aso-called smart phone or a wearable device, have become widespread, andthereby reducing power consumption of the solid-state imaging element isnecessary. For example, in the related art, a speed increase is attainedby increasing the number of column parallel AD converters describedabove. But, in doing so, the power consumption increases in proportionto the number of column parallel AD converters, and thus it is difficultto improve power efficiency (i.e., speed/power). That is, the powerconsumption increases as the speed increases, and the speed decreasesaccording to a low-power consumption.

It is desirable to increase the speed while consuming low power.

Solution to Problem

An imaging device according to a first embodiment of the presentdisclosure includes a pixel array including a plurality of pixelstwo-dimensionally arranged in a matrix pattern, a plurality of columnsignal lines disposed according to a first column of the pixels, whereinat least one column signal line of the plurality of column signal linesis connected to two or more pixels in the first column, and an analog todigital converter shared by the plurality of column signal lines.

An electronic apparatus according to a second embodiment of the presentdisclosure includes an optical system including at least one lens and animaging element configured to receive light through the optical system,wherein the imaging element includes: a pixel array including pixelstwo-dimensionally arranged in a matrix pattern, a plurality of columnsignal lines disposed according to a first column of the pixels, whereinat least one column signal line of the plurality of column signal linesis connected to two or more pixels in the first column, and an analog todigital converter shared by the plurality of column signal lines.

A comparator according to a third embodiment of the present disclosureincludes a first differential pair unit connected to a first columnsignal line of an imaging device and a second differential pair unitconnected to a second column signal line of the imaging device, whereinthe first column signal line and the second column signal line are forthe same column of pixel array units in a pixel array.

Advantageous Effects of Invention

According to an embodiment of the present disclosure, it is possible toattain a speed increase with a low-power consumption.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a block diagram illustrating a configuration example accordingto an embodiment of an imaging element to which the present technologyis applied.

FIG. 2 is a block diagram illustrating a configuration example of apixel and a column processing unit.

FIG. 3 is a timing chart for explaining an operation of an AD conversionof the imaging element.

FIG. 4 is a timing chart for explaining an operation of an AD conversionof an imaging element of the related art.

FIG. 5 is a timing chart for explaining an operation of an AD conversionof the imaging element of the related art to which a sample and holdtechnology is employed.

FIG. 6 is a block diagram illustrating a portion of a configurationexample according to a second embodiment of the imaging element.

FIG. 7 is a block diagram illustrating a portion of a configurationexample according to a third embodiment of the imaging element.

FIG. 8 is a diagram illustrating a sequence of CDS processing that isperformed by the imaging element.

FIG. 9 is a diagram illustrating a sequence of CDS processing that isperformed by the imaging element.

FIG. 10 is a block diagram illustrating a portion of a configurationexample according to a fourth embodiment of the imaging element.

FIG. 11 is a diagram illustrating a first configuration example of awiring layout of the imaging element.

FIG. 12 is a view illustrating a portion corresponding to a XII-XIIcross section of FIG. 11 .

FIG. 13 is a view illustrating portion corresponding to a XIII-XIIIcross section of FIG. 11 .

FIG. 14 is a diagram illustrating a second configuration example of awiring layout of the imaging element.

FIG. 15 is a view illustrating portion corresponding to a XV-XV crosssection of FIG. 14 .

FIG. 16 is a view illustrating portion corresponding to a XVI-XVI crosssection of FIG. 14 .

FIG. 17 is a diagram illustrating a circuit configuration of acomparator.

FIG. 18 is a timing chart for explaining a drive of the comparator.

FIG. 19 is a diagram illustrating a first modification example of acircuit configuration of the comparator.

FIG. 20 is a diagram illustrating a second modification example of acircuit configuration of the comparator.

FIG. 21 is a diagram illustrating a third modification example of acircuit configuration of the comparator.

FIG. 22 is a diagram illustrating a fourth modification example of acircuit configuration of the comparator.

FIG. 23 is a timing chart for explaining a drive of the imaging element.

FIG. 24 is a diagram illustrating disposal of a pixel of the timingchart of FIG. 23 .

FIG. 25 is a timing chart for explaining a dummy read control of atransfer signal.

FIG. 26 is a timing chart for explaining a dummy read control of a resetsignal.

FIG. 27 is a diagram illustrating a configuration example of a portionof a pixel area and a vertical drive circuit.

FIG. 28 is a diagram for explaining a system separation of a negativepotential of the related art.

FIG. 29 is a diagram for explaining a system separation of a negativepotential of the imaging element.

FIG. 30 is a block diagram illustrating a configuration example of anembodiment of an imaging device to which the present technology isapplied.

FIG. 31 is a diagram illustrating a usage example in which an imagesensor is used.

DESCRIPTION OF EMBODIMENTS

Hereinafter, a specific embodiment to which the present technology isapplied will be described in detail with reference to the drawings.

FIG. 1 is a block diagram illustrating a configuration example accordingto a first embodiment of an imaging element to which the presenttechnology is applied.

As illustrated in FIG. 1 , an imaging element 11 is configured toinclude a pixel area 12, a vertical drive circuit 13, a column signalprocessing circuit 14, a horizontal drive circuit 15, an output circuit16, a ramp signal generation circuit 17, and a control circuit 18.

The pixel area 12 is a light-receiving surface for receiving light thatis collected by an optical system, which is not illustrated. A pluralityof pixels 21 is disposed in a matrix in the pixel area 12, each pixel 21is connected to the vertical drive circuit 13 in each row via thehorizontal signal line 22, and is connected to the column signalprocessing circuit 14 in each column via the vertical signal line 23.The plurality of pixels 21 outputs pixel signals with levelscorresponding to an amount of light that is received, respectively, andan image of a subject that is imaged on the pixel area 12 is constructedfrom the pixel signals.

The vertical drive circuit 13 sequentially supplies drive signals fordriving (i.e., transferring, selecting, resetting, or the like) therespective pixels 21 to each row of the plurality of pixels 21 disposedin the pixel area 12, via the horizontal signal line 22 to the pixels21.

The column signal processing circuit 14 performs correlated doublesampling (CDS) processing with respect to a pixel signal that is outputfrom the plurality of pixels 21 via the vertical signal line 23, andthereby an AD conversion of the pixel signal is performed and resetnoise is removed. For example, the column signal processing circuit 14is configured to include a plurality of column processing units 41(refer to FIG. 2 described later) corresponding to the number of columnsof the pixels 21, and can perform in parallel with the CDS processingfor each column of the pixels 21.

The horizontal drive circuit 15 supplies a drive signal, which is usedto output pixel signals that are sequentially transferred from eachcolumn of the plurality of pixels 21 disposed in the pixel area 12 tothe data output signal line 24 from the column signal processing circuit14, to the column signal processing circuit 14.

The output circuit 16 amplifies the pixel signal that is supplied viathe data output signal line 24 from the column signal processing circuit14 at a timing according to the drive signal of the horizontal drivecircuit 15, and outputs the amplified signal to a signal processingcircuit of a subsequent stage.

The ramp signal generation circuit 17 generates a ramp signal of avoltage (i.e., slope voltage) that drops with a constant slope accordingto the lapse of time, as a reference signal that is used when the columnsignal processing circuit 14 performs an AD conversion of the pixelsignal, and supplies the ramp signal to the column signal processingcircuit 14.

The control circuit 18 drives each of the internal blocks of the imagingelement 11. For example, the control circuit 18 generates block signalsaccording to drive periods of each block, and supplies the block signalsto respective blocks. In addition, for example, the control circuit 18performs a control for reading the pixel signal from the pixel 21 suchthat the AD conversion of the pixel signal can be performed at a highspeed in the column signal processing circuit 14.

Next, FIG. 2 illustrates a configuration example of the pixel 21 of theimaging element 11 and the column processing unit 41.

FIG. 2 illustrates two pixels 21 a and 21 b that are disposed inparallel in a predetermined column, among the plurality of pixels 21disposed in the pixel area 12 in FIG. 1 . In addition, FIG. 2illustrates the column processing unit 41 that is disposed so as tocorrespond to the column, among the plurality of column processing units41 that is included in the column signal processing circuit 14.

As illustrated in FIGS. 1 and 2 , in the imaging element 11, two signallines including a first vertical signal line 23 a and a second signalline 23 b are provided in one column of the pixels 21. The pixel 21 a(e.g., pixel 21 in an odd-numbered row) is connected to the firstvertical signal line 23 a, and the pixel 21 b (e.g., pixel 21 in aneven-numbered row) is connected to the second vertical signal line 23 b.In addition, a constant current source 42 a that configures a sourcefollower circuit is connected to the first vertical signal line 23 a,and a constant current source 42 b that configures a source followercircuit is connected to the second vertical signal line 23 b. The firstvertical signal line 23 a and the second vertical signal line 23 b areconnected to the one column processing unit 41 that is disposed so as tocorrespond to the column.

The pixel 21 a is configured to include a PD 31 a, a transfer transistor32 a, an FD unit 33 a, an amplification transistor 34 a, a selectiontransistor 35 a, and a reset transistor 36 a.

The PD 31 a is a photoelectric conversion unit that photoelectricallyconverts incident light into charges and stores the charges. An anodeterminal of the PD 31 a is grounded and a cathode terminal thereof isconnected to the transfer transistor 32 a.

The transfer transistor 32 a is driven by a transfer signal TRG that issupplied from the vertical drive circuit 13, and if the transfertransistor 32 a is turned on, the charges that are stored in the PD 31 aare transferred to the FD 33 a.

The FD 33 a is a floating diffusion area having a predetermined storagecapacitor that is connected to a gate electrode of the amplificationtransistor 34 a, and stores the charges that are transferred from the PD31 a.

The amplification transistor 34 a outputs the pixel signal with a level(that is, a potential of the FD unit 33 a) according to the charges thatare stored in the FD unit 33 a, to the first vertical signal line 23 avia the selection transistor 35 a. That is, due to a configuration inwhich the FD unit 33 a is connected to the gate electrode of theamplification transistor 34 a, the FD unit 33 a and the amplificationtransistor 34 a function as a conversion unit that converts the charges,which are generated in the PD 31 a into the pixel signal with the levelaccording to the charges.

The selection transistor 35 a is driven by a selection signal SEL thatis supplied from the vertical drive circuit 13, and if the selectiontransistor 35 a is turned on such that the selection transistor 35 a isin an on state, the pixel signal that is output from the amplificationtransistor 34 a can be output to the first vertical signal line 23 a.

The reset transistor 36 a is driven by a reset signal RST that issupplied from the vertical drive circuit 13, and if the reset transistor36 a is turned on, the charges that are stored in the FD unit 33 a aredischarged to a power supply wire Vdd; thereby, the FD unit 33 a isreset.

In addition, in the same manner as the pixel 21 a, the pixel 21 b isconfigured to include a PD 31 b, a transfer transistor 32 b, an FD unit33 b, an amplification transistor 34 b, a selection transistor 35 b, anda reset transistor 36 b. Thus, since each unit of the pixel 21 boperates in the same and/or similar manner as each unit of the pixel 21a described above, a detailed description thereof will be omitted. Inaddition, hereinafter, if it is not necessary to distinguish between thepixel 21 a and the pixel 21 b, the pixels 21 a and 21 b will be simplyreferred to as the pixel 21, and each unit that configures the pixel 21is referred to in the same manner, as appropriate.

The column processing unit 41 is configured to include two inputswitches 51 a and 51 b, a comparator 52, a counter 53, and an outputswitch 54.

An input terminal on a negative side of the comparator 52 is connectedto the first vertical signal line 23 a via the input switch 51 a, and isconnected to the second vertical signal line 23 b via the input switch51 b. In addition, an input terminal on a positive side of thecomparator 52 is connected to the ramp signal generation circuit 17 onFIG. 1 . An output terminal of the comparator 52 is connected to aninput terminal of the counter 53, and an output terminal of the counter53 is connected to the data output signal line 24 via the output switch54.

The input switches 51 a and 51 b are closed and opened by the control ofthe control circuit 18 in FIG. 1 , and switch connection between theinput terminal on the negative side of the comparator 52 and the firstvertical signal line 23 a and the second vertical signal line 23 b. Forexample, if the input switch 51 a is closed and the input switch 51 b isopened, the input terminal on the negative side of the comparator 52 isconnected to first vertical signal line 23 a, and then the pixel signalthat is output from the pixel 21 a is input to the comparator 52.Meanwhile, if the input switch 51 b is closed and the input switch 51 ais opened, the input terminal on the negative side of the comparator 52is connected to second vertical signal line 23 b, and then the pixelsignal that is output from the pixel 21 b is input to the comparator 52.

The comparator 52 compares magnitudes of the ramp signal that is inputto the input terminal on the positive side and the pixel signal that isinput to the input terminal on the negative side, and outputs acomparison result signal that indicates the comparison result. Forexample, the comparator 52 outputs the comparison result signal having ahigh level when the ramp signal is greater than the analog pixel signal,and outputs the comparison result signal having a low level when theramp signal is equal to or less than the analog pixel signal.

For example, the counter 53 counts the number of clocks from a time whena potential of the ramp signal that is output from the ramp signalgeneration circuit 17 starts to drop with a constant slope to a timewhen the comparison result signal that is output from the comparator 52is switched from a high level to a low level. Thus, the value that iscounted by the counter 53 becomes a value according to the level of thepixel signal that is input to the comparator 52, and thereby the analogpixel signal that is output from the pixel 21 is converted into adigital value.

As another example, in the imaging element 11, the pixel signalcorresponding to a reset level in which the FD unit 33 of the pixel 21is reset, and the pixel signal corresponding to a signal level where theFD unit 33 of the pixel 21 retains the charges that are obtained byphotoelectric conversion of the PD 31, are output from the pixel 21.Then, when the column processing unit 41 performs the AD conversion ofthe pixel signal, an output signal in which reset noise is removed byacquiring a difference between the signals is output. In addition, thecounter 53 includes a retention unit 55 that retains the counted value;such counted value may be temporarily retained, as will be describedlater.

The output switch 54 is closed or opened by a drive signal that isoutput from the horizontal drive circuit 15. For example, if the pixelsignal in a column for which a predetermined column processing unit 41is disposed is output, the output switch 54 is closed by the drivesignal that is output from the horizontal drive circuit 15, and anoutput terminal of the counter 53 is connected to the data output signalline 24. Accordingly, the pixel signal that is obtained by the ADconversion of the column processing unit 41 is output to the data outputsignal line 24.

The imaging element 11 is configured in this way, and the columnprocessing unit 41 can alternately perform the AD conversions of thepixel signal that is output from the pixel 21 a and the pixel signalthat is output from the pixel 21 b. Thus, the imaging element 11 cancontrol reading of the pixel signal, in such a manner that settling ofthe pixel signal obtained by performing a reset operation or a signaltransfer operation of one of the pixel 21 a and the pixel 21 b can bealternately and repeatedly performed concurrently with the processing ofthe AD conversion. Thus, the AD conversion may be performed by thecolumn processing unit 41 for the pixel signal which is output from theother pixel.

In this way, the column processing unit 41 alternately switches thepixel signals of the pixel 21 a and the pixel 21 b and performs the ADconversion concurrently with the settling of the respective pixelsignals of the pixel 21 a and the pixel 21 b; thus, it is possible tospeed up the AD conversion of the column processing unit 41. Inaddition, the imaging element 11 can speed up the AD conversion withoutan increase in the number of the column processing units 41; thus, anincrease in power consumption can be avoided. That is, the imagingelement 11 can attain a speed increase of the AD conversion with alow-power consumption.

Next, FIG. 3 illustrates a timing chart for explaining an operation ofthe AD conversion of the imaging element 11.

FIG. 3 illustrates, sequentially from the top, the operation of thepixel 21 a that is connected to the first vertical signal line 23 a, theoperation of the pixel 21 b that is connected to the second verticalsignal line 23 b, and the operation of the column processing unit 41.

To begin with, in a first operation period, the pixel 21 a that isconnected to the first vertical signal line 23 a resets the FD unit 33 aand holds until the output of the pixel signal corresponding to a resetlevel is sufficiently settled (i.e., reset period). Concurrently withthis operation, in the first operation period, the pixel 21 b that isconnected to the second vertical signal line 23 b retains the output ofthe pixel signal corresponding to a signal level according to an amountof light in the PD 31 b that is settled in a previous operation period.Then, the column processing unit 41 performs the AD conversion of thepixel signal corresponding to the signal level that is output from thepixel 21 b (AD conversion period). At this time, in the columnprocessing unit 41, the counter 53 retains the counted value, accordingto the pixel signal with the signal level of the pixel 21 b, in theretention unit 55.

Next, in a second operation period, the pixel 21 a that is connected tothe first vertical signal line 23 a retains the output of the pixelsignal corresponding to a reset level that is settled in the firstoperation period and the column processing unit 41 performs an ADconversion of the reset level that is output from the pixel 21 a. Inaddition, at this time, the column processing unit 41 retains thecounted value corresponding to the reset level of the pixel 21 a, in theretention unit 55. Concurrently with this operation, in the secondoperation period, the pixel 21 b that is connected to the secondvertical signal line 23 b resets the FD unit 33 b and holds until theoutput of the pixel signal corresponding to the reset level issufficiently settled.

In a third operation period, the pixel 21 a that is connected to thefirst vertical signal line 23 a transfers the charges that are obtainedby the PD 31 a to the FD unit 33 a and holds until an output of thepixel signal corresponding to a signal level according to an amount oflight received at the PD 31 a is sufficiently settled (signal transferperiod). Concurrently with this operation, in the third operationperiod, the pixel 21 b that is connected to the second vertical signalline 23 b retains the output of the pixel signal corresponding to areset level that is settled in the second operation period and thecolumn processing unit 41 performs an AD conversion of the reset levelthat is output from the pixel 21 b. Then, the column processing unit 41acquires a difference between the counted value corresponding to thereset level and the counted value corresponding to the signal level ofthe pixel 21 b that is retained in the retention unit 55, and outputs apixel signal corresponding to a pixel signal in which reset noise hasbeen removed.

In a fourth operation period, the pixel 21 a that is connected to thefirst vertical signal line 23 a retains an output of the pixel signalcorresponding to the signal level that is settled in the third operationperiod, and the column processing unit 41 performs an AD conversion ofthe pixel signal corresponding to the signal level that is output fromthe pixel 21 a. Then, the column processing unit 41 acquires adifference between the counted value corresponding to the pixel signalof the signal and the counted value corresponding to the reset level ofthe pixel 21 a that is retained in the retention unit 55, and outputs apixel signal corresponding to a pixel signal in which the reset noisehas been removed. Concurrently with this operation, in the fourthoperation period, the pixel 21 b that is connected to the secondvertical signal line 23 b transfers the charges that are obtained by thePD 31 b to the FD unit 33 b and holds until the output of the pixelsignal corresponding to a signal level according to an amount of lightreceived at the PD 31 b is sufficiently settled.

After the fourth operation period is ended, the processing returns tothe first operation period, and hereinafter, in the same manner asabove, the pixels 21 a and the pixels 21 b in subsequent rows are set asthe operation targets, and sequentially the operations from the firstoperation period to the fourth operation period are repeatedlyperformed. In addition, in the pixel 21 a and the pixel 21 b, ahalf-period shift with each operation period may be performed.

As described above, in the imaging element 11, the AD conversion of oneof the pixel signals of the pixel 21 a and the pixel 21 b is performedconcurrently with the settling of the pixel signal of the other pixel.Accordingly, for example, the AD conversion of the pixel signalcorresponding to the signal level of the pixel 21 b in the firstoperation period is completed, and immediately after that, the ADconversion of the pixel signal corresponding to the reset level of thepixel 21 a in the second operation period is completed. In the samemanner, the AD conversion of the pixel signal corresponding to the resetlevel of the pixel 21 a in the second operation period is completed, andimmediately after that, the AD conversion of the pixel signalcorresponding to the reset level of the pixel 21 b in the thirdoperation period is completed. Furthermore, the AD conversion of thepixel signal corresponding to the reset level of the pixel 21 b in thethird operation period is completed, and immediately after that, the ADconversion of the pixel signal with the signal level of the pixel 21 ain the fourth operation period is completed. Since each of the pixelsignals with the signal level of the pixel 21 a in the fourth operationperiod and the pixel signal with the signal level of the pixel 21 b inthe first operation period corresponds to an amount of chargeaccumulated in a respective photodiode and transferred to a respectivefloating diffusion area having a preexisting charge corresponding to areset level, the reset level, or reset noise, may be removed such that apixel signal corresponding to a pixel signal in which a reset noise hasbeen removed can be obtained.

Thus, the imaging element 11 can perform the AD conversion at a higherspeed compared to the configuration in which the column processing unit41 holds the AD conversion until the settling of the pixel signal iscompleted, for example.

Here, an operation of the AD conversion of the imaging element of therelated art will be described with reference to a timing chartillustrated in FIG. 4 .

The imaging element of the related art is configured to include onevertical signal line with respect to one column of pixels, and in afirst operation period, the pixel resets a FD unit, holds until anoutput of a pixel signal with a reset level is sufficiently settled, anda column processing unit does not perform processing. Next, in a secondoperation period, the pixel continues to retain the output of the pixelsignal with the reset level that is settled in the first operationperiod, and the column processing unit performs an AD conversion of thepixel signal corresponding to the reset level that is output from thepixel.

After the AD conversion is completed, in a third operation period, thepixel transfers the charges that are obtained by photoelectricconversion of a PD to the FD unit, and holds until an output of thepixel signal with the signal level according to an amount of receivedlight of the PD is sufficiently settled, and the column processing unitdoes not perform the processing. Then, in a fourth operation period, thepixel continues to retain the output of the pixel signal with the signallevel that is settled in the third operation period, and the columnprocessing unit performs the AD conversion of the pixel signal with thesignal level that is output from the pixel.

In this way, in the imaging element of the related art, the columnprocessing unit does not perform the AD conversion while the output ofthe pixel signal is settled, and thus in order to perform the ADconversion of the pixel signal and output the signal, it is necessary toapproximately double the time, compared to an operation of the ADconversion illustrated in FIG. 3 .

In addition, some imaging elements of the related art employ asample/hold technology.

Here, an AD conversion operation of the imaging element of the relatedart that employs the sample/hold technology will be described withreference to the timing chart illustrated in FIG. 5 .

As illustrated in FIG. 5 , in the imaging element of the related art inwhich the sample/hold technology is employed, one vertical signal lineis provided in each column of the pixel, the settled pixel signal issampled and held in a capacitance element, and thus the voltage levelcan be retained. Accordingly, it is possible to perform the ADconversion of the pixel signal with the signal level that is retainedconcurrently with the settling of the pixel signal with the reset level,and to perform the AD conversion of the pixel signal with the resetlevel that is retained concurrently with the settling of the pixelsignal with the signal level.

However, in recent years, a solid-state imaging element that is used fora small terminal, such as a so-called smart phone or a wearable device,uses a fine pixel size of approximately 1 micrometer and thus it is lesspractical to employ a sample/hold technology. In addition, if acapacitance element that is used for the sample/hold is too small, noise(i.e., so-called kT/C noise) that is generated by the sample/hold isincreased. Such noise may be difficult to remove by the CDS processing,and thus the image quality is significantly degraded. In addition, ifthe capacitance element that is used for the sample/hold becomes largeto the extent that the noise does not affect the image quality, acapacitance load of the vertical signal line is increased, andaccordingly, the settling speed is decreased resulting in a decrease ifthe processing speed of the column signal processing.

In contrast to this, in the imaging element 11, since the noise does notoccur in the configuration that uses the sample/hold technology, it ispossible to avoid image quality degradation and to attain an increase inthe processing speed.

In addition, as illustrated in FIG. 3 , the imaging element 11 performsthe AD conversion processing in a sequence of performing the ADconversion of a pixel signal corresponding to the reset level of thepixel 21 a, performing the AD conversion of the pixel signalcorresponding to the reset level of the pixel 21 b, performing the ADconversion of the pixel signal corresponding to the signal level of thepixel 21 a, and performing the AD conversion of the pixel signalcorresponding to the signal level of the pixel 21 b. For example, thepixel signal is read in the same sequence even in the solid-stateimaging element that is disclosed in the PTL 2 described above, but itis different from the imaging element 11 in that the AD conversion isrepeated with respect to the pixel signal with the same reset level andsignal level. Accordingly, the imaging element 11 has a circuitconfiguration or an operation sequence of the column processing unit 41for removing the kT/C noise, which is different from the solid-stateimaging element of PTL 2.

Next, FIG. 6 is a block diagram illustrating a portion of aconfiguration of a second embodiment of the imaging element 11. In animaging element 11, as illustrated in FIG. 6 , the same symbols orreference numerals are attached to the same configurations as those ofthe imaging element 11 illustrated in FIG. 2 , and detailed descriptionthereof will be omitted.

As illustrated in FIG. 6 , the imaging element 11A has a differentconfiguration from the imaging element 11 illustrated in FIG. 2 in thata plurality of pixels 21 employs a pixel-sharing structure in which aportion configuring the pixel 21, such as the FD unit 33 or theamplification transistor 34, is shared.

A sharing pixel 61 that configures the imaging element 11A employs apixel-sharing structure that is formed by eight pixels 21, which aredisposed in a matrix of 4×2. The imaging element 11A has a configurationin which color filters are disposed on the pixels 21 according to aso-called Bayer pattern, and in FIG. 6 , colors (R, G, B) of therespective color filters are illustrated in the pixels 21.

In addition, also in the imaging element 11A, in the same manner as theimaging element 11 of FIG. 2 , the first vertical signal line 23 a andthe second vertical signal line 23 b are provided in each column inwhich the sharing pixel 61 is disposed, and a pixel signal that is inputto the comparator 52 can be switched by the input switches 51 a and 51b.

Thus, in the imaging element 11A, the AD conversion of a pixel signalwith a signal level and the AD conversion of a pixel signal with a resetlevel is alternately performed by the pixels 21 that are respectivelyincluded in two sharing pixels of a sharing pixel 61 a and a sharingpixel 61 b, which are arranged in a column direction. Then, if the ADconversion of the pixel signals of the eight pixels 21 included in thesharing pixel 61 a and the sharing pixel 61 b concludes, the sharingpixel 61 a and the sharing pixel 61 b in the subsequent row are set as aprocessing target, and the AD conversion is repeatedly performed.

In this way, in the imaging element 11A that employs the pixel-sharingstructure, in the same manner as the imaging element 11 in FIG. 2 , itis possible to attain a speed increase of the AD conversion with alow-power consumption.

Next, FIG. 7 is a block diagram illustrating a portion of aconfiguration example according to a third embodiment of the imagingelement 11. In an imaging element 11B illustrated in FIG. 7 , the samesymbols or reference numerals are attached to the same configurations asthose of the imaging element 11A illustrated in FIG. 6 , and detaileddescription thereof will be omitted.

That is, the imaging element 11B has a different configuration from theimaging element 11A of FIG. 6 in that auto-zero technology is used toimprove one or more characteristics. Specifically, in the imagingelement 11B, a capacitor 71 a is connected between the input switch 51 aand the input terminal on the negative side of the comparator 52, and acapacitor 71 b is connected between the input switch 51 b and the inputterminal on the negative side of the comparator 52. In addition, in theimaging element 11B, the input terminal on the positive side of thecomparator 52 is connected to the ramp signal generation circuit 17(refer to FIG. 1 ) via a capacitor 72, and an output terminal of thecomparator 52 is connected to the input terminal on the negative sidevia a feedback switch 73.

Thus, the imaging element 11B is configured to offset the noise (kT/Cnoise) that is generated by the sampling utilizing CDS processingperformed by the column processing unit 41.

A sequence of the CDS processing performed by the imaging element 11Bwill be described with reference to FIG. 8 and FIG. 9 .

To begin with, as illustrated in an upper stage of FIG. 8 , in a firststep, the input switch 51 a and the feedback switch 73 are closed. Next,as illustrated in a middle stage of FIG. 8 , in a second step, thefeedback switch 73 is opened, the ramp signal starts to fall, and the ADconversion of the pixel signal corresponding to a reset level that isinput via the first vertical signal line 23 a is performed.

After that, as illustrated in a lower stage of FIG. 8 , in a third step,the input switch 51 a is opened, and the input switch 51 b and thefeedback switch 73 are closed. Then, as illustrated in an upper stage ofFIG. 9 , in a fourth step, the feedback switch 73 is opened, the rampsignal starts to fall, and the AD conversion of the pixel signalcorresponding to a reset level that is input via the second verticalsignal line 23 b is performed.

Furthermore, as illustrated in a middle stage of FIG. 9 , in a fifthstep, the input switch 51 b is opened, the input switch 51 a is closed,the ramp signal starts to fall, and the AD conversion of the pixelsignal corresponding to a signal level that is input via the firstvertical signal line 23 a is performed. Then, as illustrated in a lowerstage of FIG. 9 , in a sixth step, the input switch 51 a is opened, theinput switch 51 b is closed, the ramp signal starts to fall, and the ADconversion of the pixel signal corresponding to a signal level that isinput via the second vertical signal line 23 b is performed.

Here, in the transition from the first step to the second step, the kT/Cnoise is applied to the capacitor 71 a connected to the first verticalsignal line 23 a. After that, in the transition from the third step tothe fifth step, one side of the capacitor becomes an open end (highimpedance node) such that capacitance charges do not move; thus, a newapplication of the kT/C noise is avoided. Thus, by acquiring adifference between the results of the AD conversion from the first stepto the fifth step, and by performing the digital CDS processing, it ispossible to offset the kT/C noise.

Accordingly, the imaging element 11B can capture an image with lessnoise, can avoid image quality degradation, and can attain an increasein speed of the processing speed.

Next, FIG. 10 is a block diagram illustrating a portion of aconfiguration example according to the third embodiment of the imagingelement 11. In an image element 11C illustrated in FIG. 10 , the samesymbols or reference numerals are attached to the same configurations asthose of the imaging element 11B illustrated in FIG. 7 , and detaileddescription thereof will be omitted.

As illustrated in FIG. 10 , the imaging element 11C has a differentconfiguration from the imaging element 11B of FIG. 7 in that fourvertical signal lines of a first vertical signal line 23 a-1, a secondvertical signal line 23 b-1, a third vertical signal line 23 a-2, and afourth vertical signal line 23 b-2 are provided in each column of thesharing pixel 61, and two column processing units 41-1 and 41-2 arerespectively provided on an upper side and a lower side with respect toa column direction of the pixel area. That is, the imaging element 11Chas a configuration in which the third vertical signal line 23 a-2, thefourth vertical signal line 23 b-2, and the column processing unit 41-2are added. In addition, a constant current source 42 a-1 is connected tothe first vertical signal line 23 a-1, a constant current source 42 b-1is connected to the second vertical signal line 23 b-1, a constantcurrent source 42 a-2 is connected to the third vertical signal line 23a-2, and a constant current source 42 b-2 is connected to the fourthvertical signal line 23 b-2.

In the imaging element 11C, the sharing pixel 61 a-1 is connected to thecolumn processing unit 41-1 via the first vertical signal line 23 a-1,and the sharing pixel 61 b-1 is connected to the column processing unit41-1 via the second vertical signal line 23 b-1. In addition, in theimaging element 11C, the sharing pixel 61 a-2 is connected to the columnprocessing unit 41-2 via the third vertical signal line 23 a-2, and thesharing pixel 61 b-2 is connected to the column processing unit 41-2 viathe fourth vertical signal line 23 b-2.

Thus, in the imaging element 11C, the AD conversion of the pixel signalcorresponding to the signal level and the AD conversion of the pixelsignal corresponding to the reset level are alternately performed by thepixels 21 that are respectively included in each of the sharing pixel 61a-1 and the sharing pixel 61 b-1, in the column processing unit 41-1.Concurrently with this, in the imaging element 11C, the AD conversion ofthe pixel signal corresponding to the signal level and the AD conversionof the pixel signal corresponding to the reset level are alternatelyperformed by the pixels 21 that are respectively included in each of thesharing pixel 61 a-2 and the sharing pixel 61 b-2, in the columnprocessing unit 41-2.

In this way, in the imaging element 11C, the column processing unit 41-1and the column processing unit 41-2 can concurrently perform the ADconversions, and thus, for example, it is possible to double the speedat which the AD conversion is performed as compared to the imagingelement 11B in FIG. 7 .

As described above, the imaging elements 11, according to eachembodiment described above, have a configuration in which theabove-described sample/hold technology is not used, and the number ofthe column processing units 41 is not increased. It is possible torealize a speed increase of the AD conversion processing without anincrease in the power consumption. That is, it is possible to increasepower efficiency of the imaging element 11, which can perform fastprocessing.

Next, a wiring layout of the imaging element 11 will be described.

To begin with, a first configuration example of a wire layout of theimaging element 11 will be described with reference to FIGS. 11 to 13 .FIG. 11 illustrates a planar configuration of the pixel 21 a and thepixel 21 b that are included in the imaging element 11. FIG. 12illustrates a cross-sectional configuration of a section correspondingto a XII×XII cross section illustrated in FIG. 11 , that is, aconnection section that connects the pixel 21 a to the first verticalsignal line 23 a. FIG. 13 illustrates a cross-sectional configuration ofa section corresponding to a XIII×XIII cross section illustrated in FIG.11 , that is, a connection section that connects the pixel 21 b to thesecond vertical signal line 23 b is illustrated.

As illustrated in FIG. 11 , the pixel 21 a is configured to include thePD 31 a, the transfer transistor 32 a, the FD unit 33 a, theamplification transistor 34 a, the selection transistor 35 a, and thereset transistor 36 a. In addition, a horizontal signal line VSS-athrough which a source voltage is supplied, a horizontal signal line22TRG-a through which a row transfer pulse is supplied to a transfertransistor 32 a, a horizontal signal line 22RST-a through which a rowreset pulse is supplied to the reset transistor 36 a, a horizontalsignal line VDD-a through which a drain voltage is supplied, and ahorizontal signal line 22SEL-a through which a row selection pulse issupplied to the selection transistor 35 a, are disposed along ahorizontal direction of the pixel 21 a.

In the same manner, the pixel 21 b is configured to include the PD 31 b,the transfer transistor 32 b, the FD unit 33 b, the amplificationtransistor 34 b, the selection transistor 35 b, and the reset transistor36 b. In addition, a horizontal signal line VSS-b through which a sourcevoltage is supplied, a horizontal signal line 22TRG-b through which arow transfer pulse is supplied to a transfer transistor 32 b, ahorizontal signal line 22RST-b through which a row reset pulse issupplied to the reset transistor 36 b, a horizontal signal line VDD-bthrough which a drain voltage is supplied, and a horizontal signal line22SEL-b through which a row selection pulse is supplied to the selectiontransistor 35 b, are disposed along the horizontal direction of thepixel 21 b.

In addition, the first vertical signal line 23 a and the second verticalsignal line 23 b are disposed along a vertical direction in which thepixel 21 a and the pixel 21 b are arranged. Then, an inter-signal-lineshield 101 is disposed between the first vertical signal line 23 a andthe second vertical signal line 23 n. The inter-signal-line shield 101is connected to the horizontal signal line 22VSS-a and the horizontalsignal line 22VSS-b, and is fixed to the source voltage.

Here, since uniformity of shape is generally important in the pixellayout, the pixel 21 a and the pixel 21 b have the same configurationother than a connection section of the pixel 21 a and the first verticalsignal line 23 a, and a connection section of the pixel 21 b and thesecond vertical signal line 23 b. That is, the connection section of thefirst pixel 21 a and the first vertical signal line 23 a that areillustrated in FIG. 12 has a different configuration from the connectionsection of the pixel 21 b and the second vertical signal line 23 b thatare illustrated in FIG. 13 .

As illustrated in FIG. 12 , in the pixel 21 a, a gate layer in whichgate electrodes 122-1 a and 122-2 a are formed, a contact layer in whichcontacts 123-1 a and 123-2 a are formed, a first metal layer in whichmetal wires 124-1 a and 124-2 a are formed, a first via layer in which avia 125 a is formed, a second metal layer in which a metal wire 126 a isformed, a second via layer in which a via 127 a is formed, and a thirdmetal layer in which the first vertical signal line 23 a, the secondvertical signal line 23 b, and the inter-signal-line shield 101 areformed, are sequentially laminated from a semiconductor substrate (Well)121 side.

The metal wire 124-1 a is connected to the FD unit 33 a in FIG. 11 , andis connected via the contact 123-1 a to the gate electrode 122-1 a thatconfigures the amplification transistor 34 a. Thus, a potential with alevel corresponding to the charges stored in the FD unit 33 a is appliedto the gate electrode 122-1 a via the metal wire 124-1 a and the contact123-1 a.

The gate electrode 122-2 a configures the selection transistor 35 a andis connected to the horizontal signal line 22SEL-a through which the rowselection pulse is supplied, as illustrated in FIG. 11 . Then, adiffusion layer on a source side of the selection transistor 35 a isconnected to the first vertical signal line 23 a via the contact 123-2a, the metal wire 124-2 a, the via 125 a, the metal wire 126 a, and thevia 127 a.

In addition, as illustrated in FIG. 13 , in the pixel 21 b, in the samemanner as the pixel 21 a, gate electrodes 122-1 b and 122-2 b are formedin a gate layer, contacts 123-1 b and 123-2 b are formed in a contactlayer, metal wires 124-1 b and 124-2 b are formed in a first metallayer, a via 125 b is formed in a first via layer, a metal wire 126 b isformed in a second metal layer, a via 127 b is formed in a second vialayer, and the first vertical signal line 23 a, the second verticalsignal line 23 b, and the inter-signal-line shield 101 are formed in thethird metal layer.

The metal wire 124-1 b is connected to the FD unit 33 b in FIG. 11 , andis connected via the contact 123-1 b to the gate electrode 122-1 b thatconfigures the amplification transistor 34 b. Thus, a potential with alevel corresponding to the charges stored in the FD unit 33 b is appliedto the gate electrode 122-1 b via the metal wire 124-1 b and the contact123-1 b.

The gate electrode 122-2 b configures the selection transistor 35 b andis connected to the horizontal signal line 22SEL-b through which the rowselection pulse is supplied, as illustrated in FIG. 11 . Then, adiffusion layer on a source side of the selection transistor 35 b isconnected to the second vertical signal line 23 b through the contact123-2 b, the metal wire 124-2 b, the via 125 b, the metal wire 126 b,and the via 127 b.

As illustrated in FIG. 12 and FIG. 13 , in the third metal layer, theinter-signal-line shield 101 that is fixed to the source voltage isdisposed between the first vertical signal line 23 a and the secondvertical signal line 23 b. Thus, it is possible to prevent a couplingcapacitance from being directly generated between the first verticalsignal line 23 a and the second vertical signal line 23 b, in, forexample, the third metal layer. Thus, even if a read operation, such asconcurrently and alternately switching the AD conversion and settling ofthe pixel signal is performed, it is possible to prevent the firstvertical signal line 23 a and the second vertical signal line 23 b fromaffecting each other, and for example, to prevent crosstalk noise fromoccurring.

However, in the third metal layer, the first vertical signal line 23 a,the second vertical signal line 23 b, and the inter-signal-line shield101 are disposed in a vertical direction. In the second metal layer, themetal wire 126 a and the metal wire 126 b are disposed in a horizontaldirection. That is, a wire layout is formed in such a manner that thevertical signal line 23 is alternately intersected with the metal wire126 between the third metal layer and the second metal layer.

Accordingly, as illustrated in FIG. 12 , a coupling capacitance Caoccurring between the second vertical signal line 23 b of the thirdmetal layer and the metal wire 126 a of the second metal layer, isincreased. That is, the metal wire 126 a is connected to the firstvertical signal line 23 a, and thereby the coupling capacitance Caindirectly occurs between the first vertical signal line 23 a and thesecond vertical signal line 23 b.

In the same manner, as illustrated in FIG. 13 , a coupling capacitanceCb occurring between the first vertical signal line 23 a of the thirdmetal layer and the metal wire 126 b of the second metal layer, isincreased. That is, the metal wire 126 b is connected to the secondvertical signal line 23 b, and thereby the coupling capacitance Cbindirectly occurs between the first vertical signal line 23 a and thesecond vertical signal line 23 b.

As illustrated above, in the imaging element 11, the AD conversion andthe settling of the pixel signal is concurrently performed and a readoperation of reading the pixel signal is performed in such a manner thatthe AD conversion and the settling are alternately switched, in thepixel 21 a and the pixel 21 b. In the read operation, a shift occurs inthe first vertical signal line 23 a and the second vertical signal line23 b at a timing in which the pixel signal is read. For this reason, forexample, when the settling of the pixel signal of the pixel 21 a is notperformed, if the pixel signal of the pixel 21 b is read, a potentialchange of the first vertical signal line 23 a is transferred to thesecond vertical signal line 23 b through the coupling capacitances Caand Cb, and thereby there is a possibility that a signal quality isdegraded.

As a result, noise of the pixel signal that is transferred through thefirst vertical signal line 23 a and the second vertical signal line 23 bis increased, and there is a possibility that the noise significantlyaffects the image quality. In addition, it is necessary to secure asettling time for sufficiently returning signal quality to an originalstate, and thereby there is a possibility that a speed increase may notbe realized. In this way, a negative influence can occur due tocrosstalk through the coupling capacitances Ca and Cb indirectlyoccurring between the first vertical signal line 23 a and the secondvertical signal line 23 b.

Therefore, a wiring layout that can suppress an occurrence of thenegative influence is employed in the imaging element 11.

Next, a second configuration example of the wiring layout of the imagingelement 11 will be described with reference to FIG. 14 to FIG. 16 . FIG.14 illustrates a planar configuration of the pixel 21 a and the pixel 21b that are included in the imaging element 11. FIG. 15 illustrates across-sectional configuration of a section corresponding to a XV-XVcross section illustrated in FIG. 14 , that is, a connection sectionthat connects the pixel 21 a to the first vertical signal line 23 a.FIG. 16 illustrates a cross-sectional configuration of a sectioncorresponding to a XVI-XVI cross section illustrated in FIG. 14 , thatis, a connection section that connects the pixel 21 b to the secondvertical signal line 23 b.

In the wiring layout of the imaging element 11 illustrated in FIG. 14 toFIG. 16 , the same symbols or reference numerals are attached to thesame configurations as those of the wiring layout of the imaging element11 described with reference to FIG. 11 to FIG. 13 described above, andas such, a detailed description thereof will be omitted. For example, ina second configuration example of the wiring layout of the imagingelement 11, a configuration of the connection section illustrated inFIG. 14 to FIG. 16 is different from a configuration of the wiringlayout of the imaging element 11 described with reference to FIG. 11 toFIG. 13 described above.

For example, as illustrated in FIG. 15 , in the connection section thatconnects the pixel 21 a to the first vertical signal line 23 a, themetal wire 124-3 a is formed up to a position below the second verticalsignal line 23 b in the first metal layer. In addition, in the secondmetal layer, the metal wire 126-1 a and the metal wire 126-2 a areformed so as to be separated. Then, the metal wire 126-1 a is connectedto the metal wire 124-3 a through the via 125 a, and is connected to thefirst vertical signal line 23 a through the via 127-1 a. In addition,the metal line 126-2 a is connected to the inter-signal-line shield 101through the via 127-2 a.

In this way, in the connection section that connects the pixel 21 a tothe first vertical signal line 23 a, a two-layer structure is formed bythe metal wire 124-3 a that is provided in the first metal layer, andthe metal wire 126-1 a and the metal wire 126-2 a that are provided inthe second metal layer. Then, the metal wire 126-2 a that is connectedto the inter-signal-line shield 101, which is fixed to the sourcepotential, is disposed between the second vertical signal line 23 b andthe metal wire 124-3 a. Accordingly, a shield structure in which thefirst vertical signal line 23 a is shielded with respect to the secondvertical signal line 23 b that is not used for reading the pixel signalfrom the pixel 21 a, is provided. That is, a coupling capacitance Ca′ isgenerated between the second vertical signal line 23 b and the metalwire 126-2 a, and the coupling capacitance Ca (FIG. 12 ) can be reducedbetween the first vertical signal line 23 a and the second verticalsignal line 23 b that are described above.

In the same manner, as illustrated in FIG. 16 , in the connectionsection that connects the pixel 21 b to the second vertical signal line23 b, the metal wire 124-3 b is formed up to a position below the secondvertical signal line 23 b in the first metal layer. In addition, in thesecond metal layer, the metal wire 126-1 b and the metal wire 126-2 bare formed so as to be separated. Then, the metal wire 126-2 b isconnected to the metal wire 124-3 b through the via 125 b, and isconnected to the second vertical signal line 23 b through the via 127-1b. In addition, the metal line 126-1 b is connected to theinter-signal-line shield 101 through the via 127-2 b.

In this way, in the connection section that connects the pixel 21 b tothe second vertical signal line 23 b, a two-layer structure is formed bythe metal wire 124-3 b that is provided in the first metal layer, andthe metal wire 126-1 b and the metal wire 126-2 b that are provided inthe second metal layer. Then, the metal wire 126-1 b that is connectedto the inter-signal-line shield 101 which is fixed to the sourcepotential, is disposed between the first vertical signal line 23 a andthe metal wire 124-3 b. Accordingly, a shield structure in which thesecond vertical signal line 23 b is shielded with respect to the firstvertical signal line 23 a that is not used for reading the pixel signalfrom the pixel 21 b, is provided. That is, a coupling capacitance Cb′ isgenerated between the first vertical signal line 23 a and the metal wire126-1 b, and the coupling capacitance Cb (FIG. 13 ) can be reducedbetween the first vertical signal line 23 a and the second verticalsignal line 23 b that are described above.

As described above, the imaging element 11 can configure a shieldstructure for a complementary shield, in the connection section thatconnects the pixel 21 a to the first vertical signal line 23 a, and theconnection section that connects the pixel 21 b to the second verticalsignal line 23 b.

That is, in the connection section that connects the pixel 21 a to thefirst vertical signal line 23 a, a shield structure that shields thefirst vertical signal line 23 a with respect to the second verticalsignal line 23 b is formed by connecting the metal wire 126-2 a, whichis disposed between the metal wire 124-3 a and the second verticalsignal line 23 b, to the inter-signal-line shield 101. In the samemanner, in the connection section that connects the pixel 21 b to thesecond vertical signal line 23 b, a shield structure that shields thesecond vertical signal line 23 b with respect to the first verticalsignal line 23 a is formed by connecting the metal wire 126-1 b which isdisposed between the metal wire 124-3 b and the first vertical signalline 23 a, to the inter-signal-line shield 101.

In this way, it is possible to reduce the coupling capacitance betweenthe first vertical signal line 23 a and the second vertical signal line23 b, and to suppress the occurrence of the crosstalk. Thus, it ispossible to decrease the noise of the pixel signal that is transferredthrough the first vertical signal line 23 a and the second verticalsignal line 23 b, and to obtain an image with better image quality. Inaddition, it is not necessary to secure a long settling time in order tosufficiently return the signal quality to an original state, and sincereduction in the amount of settling time is possible, it is possible toincrease the processing speed.

Thus, in the imaging element 11 that performs a read operation, such asconcurrently and alternately switching the AD conversion and settling ofthe pixel signal, it is possible to realize an increase in speed and ahigh accuracy.

The wiring layout described with reference to FIG. 14 to FIG. 16 is notlimited to the number of sharing pixels 21, the number of the verticalsignal lines 23, and a direction (includes disposal of elements,inversion disposal in a unit pixel, or the like) of the transistors thatconfigure the pixel 21, and can be applied to image element 11 withvarious configurations.

Furthermore, the present technology is not limited to a configuration inwhich two vertical signal lines 23 are disposed with respect to a pixelcolumn, as the present technology can be applied to a configuration inwhich three or more vertical signal lines 23 are disposed, and canperform a complementary shield with respect to a combination ofarbitrary vertical signal lines 23. In a configuration in which, forexample, four vertical signal lines 23 are disposed, a pair of the thirdvertical signal line 23 and the fourth vertical signal line 23 may becomplementarily shielded with respect to a pair of the first verticalsignal line 23 and the second vertical signal line 23. In thisconfiguration, the number of the metal wires 124 in the first metallayer can be reduced by the number of lines corresponding to twovertical signal lines 23, and thus it is possible to prevent a load fromincreasing.

In addition, for example, by further adding a metal layer to the firstto third metal layers described above and thereby configuring the sameshield structure, it is possible to further suppress crosstalk.

The shield structure described with reference to FIG. 14 to FIG. 16 maybe applied between inputs (between FD units 33) of, for example, asource follower circuit. That is, when a capacitance between the FDunits 33 is not ignored with respect to a plurality of FD units 33 in aunit pixel of the sharing pixel 61 illustrated in FIG. 6 , a shieldstructure may be formed between the FD units 33. Accordingly, in thereading operation, such as concurrently and alternately switching the ADconversion and the settling of the pixel signal, it is possible tosuppress the negative influence occurring between the plurality of FDunits 33 in the unit pixel.

However, as described above, the imaging element 11 is configured toswitch the inputs of the comparator 52 using the input switches 51 a and51 b. In this configuration, there is a possibility that injectionleakage and feedthrough at the time of the switching operation of theinput switches 51 a and 51 b adds noise to the comparator 52. Inaddition, there is a possibility that a resistor at the time ofswitching on the input switches 51 a and 51 b may cause a delay in thesettling of the pixel signal that is transferred through the firstvertical signal line 23 a and the second vertical signal line 23 b.Meanwhile, a mounting method is proposed, which doubles reading speed byconcurrently performing the reading operation using two comparators inorder to speed up the operation of the imaging element. But, in themounting method, there is a possibility that the size of the comparatoris doubled and current consumption is also doubled.

Therefore, the imaging element 11 employs the comparator 52 with aconfiguration in which differential pair units are provided in parallelwith each other, and switches for switching an active state and astandby state of the differential pair units are incorporated, andthereby reduce the likelihood that the size of the comparator is doubledand/or that the current consumption is also doubled. In thisconfiguration, the input switches 51 a and 51 b are not provided, andthe first vertical signal line 23 a and the second vertical signal line23 b are directly connected to the comparator 52.

FIG. 17 illustrates a circuit configuration of the comparator 52.

As illustrated in FIG. 17 , the comparator 52 is configured to include adifferential pair circuit 201, a second amplification unit (2nd AMP)202, and a third amplification unit (3rd AMP) 203.

The pixel signals from the first vertical signal line 23 a and thesecond vertical signal line 23 b, and the ramp signal from the rampsignal generation circuit 17 are input to the differential pair circuit201. Then, a differential pair output from the differential pair circuit201 is supplied to the second amplification unit 202, and then amplifiedand inverted. An output from the second amplification unit 202 isamplified up to a predetermined level by the third amplification unit203 and thereafter is output as a comparison result signal describedabove.

The differential pair circuit 201 is configured to include transistors211 to 213, a first differential pair unit 214 a, and a seconddifferential pair unit 214 b, and as illustrated in FIG. 17 , the firstdifferential pair unit 214 a and the second differential pair unit 214 bare provided in parallel.

The first differential pair unit 214 a is connected to the firstvertical signal line 23 a and the ramp signal generation circuit 17, andcompares the pixel signal that is supplied through the first verticalsignal line 23 a with the ramp signal that is supplied from the rampsignal generation circuit 17. The second differential pair unit 214 b isconnected to the second vertical signal line 23 b and the ramp signalgeneration circuit 17, and compares the pixel signal that is suppliedthrough the second vertical signal line 23 b with the ramp signal thatis supplied from the ramp signal generation circuit 17.

The first differential pair unit 214 a is configured to include a pairof capacitors 221-1 a and 221-2 a, a pair of transistors 222-1 a and222-2 a, a pair of transistors 223-1 a and 223-2 a, and a pair oftransistors 224-1 a and 224-2 a.

The capacitor 221-1 a is connected to the first vertical signal line 23a and retains a potential according to a level of the pixel signal, andthe capacitor 221-2 a is connected to the ramp signal generation circuit17 and retains a potential according to a level of the ramp signal.

A potential that is retained in the capacitor 221-1 a is applied to agate electrode of the transistor 222-1 a, and a potential that isretained in the capacitor 221-2 a is applied to a gate electrode of thetransistor 222-2 a. Thus, the pair of transistors 222-1 a and 222-2 a isused for comparing the pixel signal that is supplied through the firstvertical signal line 23 a with the ramp signal that is supplied from theramp signal generation circuit 17.

The transistor 223-1 a is disposed so as to be connected between aconnection point of the gate electrodes of the capacitor 221-1 a and thetransistor 222-1 a, and a connection point of the transistor 222-1 a andthe transistor 224-1 a. In addition, the transistor 223-2 a is disposedso as to be connected between a connection point of the gate electrodesof the capacitor 221-2 a and the transistor 222-2 a, and a connectionpoint of the transistor 222-2 a and the transistor 224-2 a. Thus, thepair of the transistors 223-1 a and 223-2 a is driven by an auto-zerocontrol signal AZP-a, and performs an auto-zero operation of the firstdifferential pair unit 214 a.

The transistor 224-1 a is disposed on a source side of the transistor222-1 a to which the potential according to the level of the pixelsignal is applied. The transistor 224-2 a is disposed on a source sideof the transistor 222-2 a to which the potential according to the levelof the ramp signal is applied. Then, the pair of transistors 224-1 a and224-2 a is driven by a comparison operation selection signal SEL-a, andis used for switching an active state and a standby state of the firstdifferential pair unit 214 a, by performing ON/OFF of power supplying tothe pair of transistors 222-1 a and 222-2 a.

That is, the pair of transistors 224-1 a and 224-2 a is turned on, andthereby the power is supplied to the pair of transistors 222-1 a and222-2 a. Accordingly, the first differential pair unit 214 a enters anactive state (ACTIVE), and the pixel signal is compared with the rampsignal. Meanwhile, the pair of transistors 224-1 a and 224-2 a is turnedoff, and thereby the power is not supplied to the pair of transistors222-1 a and 222-2 a. Accordingly, the first differential pair unit 214 aenters a standby state (Standby), and the comparison of the pixel signalwith the ramp signal is stopped.

In the same manner as the first differential pair unit 214 a, the seconddifferential pair unit 214 b is configured to include a pair ofcapacitors 221-1 b and 221-2 b, a pair of transistors 222-1 b and 222-2b, a pair of transistors 223-1 b and 223-2 b, and a pair of transistors224-1 b and 224-2 b.

Thus, the pair of transistors 224-1 b and 224-2 b is turned on, andthereby the power is supplied to the pair of transistors 222-1 b and222-2 b. Accordingly, the second differential pair unit 214 b enters anactive state, and the pixel signal is compared with the ramp signal.Meanwhile, the pair of transistors 224-1 b and 224-2 b is turned off,and thereby the power is not supplied to the pair of transistors 222-1 band 222-2 b. Accordingly, the second differential pair unit 214 b entersthe standby state, and the comparison of the pixel signal with the rampsignal is stopped.

The comparator 52 is configured in this way: the comparison operationselection signal SEL-a that is supplied to the transistors 224-1 a and224-2 a and the comparison operation selection signal SEL-b that issupplied to the transistors 224-1 b and 224-2 b are mutually inverted inlevel at the same timing. Accordingly, the active state and the standbystate of the first differential pair unit 214 a and the seconddifferential pair unit 214 b can be alternately switched.

For example, in the AD conversion periods (the above-described secondand fourth operation periods of FIG. 3 ) of the pixel signals that areoutput from the pixel 21 a connected to the first vertical signal line23 a, the first differential pair unit 214 a can be set as the activestate, and the second differential pair unit 214 b can be set as thestandby state. In addition, in the AD conversion periods (theabove-described first and third operation periods of FIG. 3 ) of thepixel signals that are output from the pixel 21 b connected to thesecond vertical signal line 23 b, the second differential pair unit 214b can be set as the active state, and the first differential pair unit214 a can be set as the standby state.

In this way, in the imaging element 11, the pixel signal that is atarget, an AD conversion of which is performed in the column processingunit 41, can be switched by the switching units (the pair of transistors224-1 a and 224-2 a, and the pair of transistors 224-1 b and 224-2 b)that are incorporated in the comparator 52.

Thus, since the imaging element 11, including the comparator 52 withsuch a configuration, can switch the inputs within the comparator 52, itis possible to configure the image element 11 without the input switches51 a and 51 b. Accordingly, it is possible to avoid a negative influencecaused by a configuration in which the input switches 51 a and 51 b areprovided, for example, noise that is generated when the input switches51 a and 51 b are switched, or a negative influence, such as a delay ofthe settling caused by an ON resistance of the input switches 51 a and51 b.

Accordingly, the imaging element 11 can capture an image with less noiseand can further attain the speed increase.

In addition, compared to a configuration in which the speed increase canbe attained by providing two comparators, the comparator 52 can attain alow-power consumption and miniaturization. That is, since the comparator52 shares a current path of the first differential pair unit 214 a andthe second differential pair unit 214 b and shares the secondamplification unit 202 and the third amplification unit 203, thecomparator 52 can be driven with the same current consumption as that ofthe configuration in which one comparator is provided, and can bemounted in an area reduced by the size of the sharing portion. Forexample, the comparator 52 can be realized by area size increase alonefor providing the first differential pair unit 214 a on an outside ofthe second differential pair unit 214 b, compared to the comparatorhaving a configuration in which only the second differential pair unit214 b is included, and thereby it is possible to reduce trade-off tochip specifications.

Next, FIG. 18 illustrates a timing chart for explaining driving of thecomparator 52.

FIG. 18 illustrates sequentially from the top, the ramp signal RAMP thatis supplied from the ramp signal generation circuit 17, the comparisonoperation selection signal SEL-a that is supplied to the pair oftransistors 224-1 a and 224-2 a, the comparison operation selectionsignal SEL-b that is supplied to the pair of transistors 224-1 b and224-2 v, the auto-zero control signal AZP-a that is supplied to the pairof transistors 223-1 a and 223-2 a, the auto-zero control signal AZP-bthat is supplied to the pair of transistors 223-1 b and 223-2 b, and thecomparison result signal VCO that is output from the comparator 52.

To begin with, in a P phase of a first cycle, while the comparisonoperation selection signal SEL-a goes to an L level and the firstdifferential pair unit 214 a enters an active state, the comparisonoperation selection signal SEL-b goes to a H level and the seconddifferential pair unit 214 b enters a standby state. In addition, theauto-zero control signal AZP-a goes to the L level and the auto-zerooperation of the first differential pair unit 214 a is performed in afirst half of the P phase of the first cycle, and thereafter the ADconversion of the pixel signal with the reset level is performed by thefirst differential pair unit 214 a. Accordingly, the comparison resultsignal VCO is inverted according to the pixel signal with the resetlevel that is input through the first vertical signal line 23 a.

Next, in a P phase of a second cycle, while the comparison operationselection signal SEL-a goes to the H level and the first differentialpair unit 214 a enters the standby state, the comparison operationselection signal SEL-b goes to the L level and the second differentialpair unit 214 b enters the active state. In addition, the auto-zerocontrol signal AZP-b goes to the L level and the auto-zero operation ofthe second differential pair unit 214 b is performed in a first half ofthe P phase of a second cycle, and thereafter the AD conversion of thepixel signal with the reset level is performed by the seconddifferential pair unit 214 b. Accordingly, the comparison result signalVCO is inverted according to the pixel signal with the reset level thatis input through the second vertical signal line 23 b.

Subsequently, in a D phase of a first cycle, while the comparisonoperation selection signal SEL-a goes to the L level and the firstdifferential pair unit 214 a enters the active state, the comparisonoperation selection signal SEL-b goes to the H level and the seconddifferential pair unit 214 b enters the standby state. Then, the ADconversion of the pixel signal with the signal level is performed by thefirst differential pair unit 214 a, and the comparison result signal VCOis inverted according to the pixel signal with the signal level that isinput through the first vertical signal line 23 a.

Then, in a D phase of a second cycle, while the comparison operationselection signal SEL-a goes to the H level and the first differentialpair unit 214 a enters the standby state, the comparison operationselection signal SEL-b goes to the L level and the second differentialpair unit 214 b enters the active state. Then, the AD conversion of thepixel signal with the signal level is performed by the seconddifferential pair unit 214 b, and the comparison result signal VCO isinverted according to the pixel signal with the signal level that isinput through the second vertical signal line 23 b.

In this way, also in the imaging element 11 that includes the comparator52 with the configuration illustrated in FIG. 17 , the CDS operationperformed by the P phase and the D phase can be performed, in the samemanner as in the related art.

In addition, as illustrated in FIG. 18 , by performing an inversionoperation of the comparison operation selection signal SEL-a and thecomparison operation selection signal SEL-b, a control of alternatelyselecting the active state and the standby state of the firstdifferential pair unit 214 a and the second differential pair unit 214 bis performed. Thus, when the comparison operation selection signal SEL-ais in the H level, the comparison operation selection signal SEL-b goesto the L level, and thereby it is possible to prevent the signal of thesecond differential pair unit 214 b in the active state from beingpropagated to the first differential pair unit 214 a in the standbystate. On the contrary, when the comparison operation selection signalSEL-b is in the H level, the comparison operation selection signal SEL-agoes to the L level, and thereby it is possible to prevent the signal ofthe first differential pair unit 214 a in the active state from beingpropagated to the second differential pair unit 214 b in the standbystate.

For example, in the comparator 52, the comparison operation selectionsignal SEL-b that is supplied to the transistors 224-1 b and 224-2 b,and the auto-zero control signal AZP-b that is supplied to thetransistors 223-1 b and 223-2 b can be constantly fixed to the H level.In this case, the first differential pair unit 214 a is constantly inthe active state, the second differential pair unit 214 b is constantlyin the standby state, and the comparator 52 can perform the same driveas that of the comparator of the related art that uses only the firstdifferential pair unit 214 a. On the contrary, when the comparisonoperation selection signal SEL-a and the auto-zero control signal AZP-aare constantly fixed to the H level, the comparator 52 can perform thesame drive as that of the comparator of the related art that uses onlythe second differential pair unit 214 b.

FIG. 19 illustrates a first modification example of a circuitconfiguration of the comparator 52.

In a comparator 52A illustrated in FIG. 19 , the same symbols orreference numerals are attached to the same configurations as those ofthe comparator 52 of FIG. 17 , and detailed description thereof will beomitted. That is, the comparator 52A is the same as the comparator 52 ofFIG. 17 in that the comparator 52A includes the second amplificationunit 202 and the third amplification unit 203 and a differential paircircuit 201A includes transistors 211 to 213. In addition, thecomparator 52A has the same configuration as that of the comparator 52of FIG. 17 in that a first differential pair unit 214 a-A and a seconddifferential pair unit 214 b-A are provided in parallel with each other.

Meanwhile, in the comparator 52A, disposal of the transistors that areused for switching the active state and the standby state of the firstdifferential pair unit 214 a-A and the second differential pair unit 214b-A is different from that of the comparator 52 of FIG. 17 .

That is, in the first differential pair unit 214 a of the comparator 52of FIG. 17 , a pair of the transistors 224-1 a and 224-2 a that is usedfor switching the active state and the standby state are respectivelydisposed on source sides of a pair of the transistors 222-1 a and 222-2a that is used for comparing signals. In addition, in the seconddifferential pair unit 214 b of the comparator 52 of FIG. 17 , a pair ofthe transistors 224-1 b and 224-2 b that is used for switching theactive state and the standby state are respectively disposed on sourcesides of a pair of the transistors 222-1 b and 222-2 b that is used forcomparing signals.

In contrast to this, the first differential pair unit 214 a-A of thecomparator 52A has a configuration in which a pair of the transistors225-1 a and 225-2 a that is used for switching the active state and thestandby state are respectively disposed on drain sides of a pair of thetransistors 222-1 a and 222-2 a that is used for comparing signals. Inthe same manner, the second differential pair unit 214 b-A of thecomparator 52A has a configuration in which a pair of the transistors225-1 b and 225-2 b that is used for switching the active state and thestandby state are respectively disposed on drain sides of a pair of thetransistors 222-1 b and 222-2 b that is used for comparing signals.

The comparator 52A is configured in this way, and can perform the drivedescribed above with reference to FIG. 18 , in the same manner as in thecomparator 52 of FIG. 17 .

Then, for example, the comparator 52A can prevent the ramp signal thatis applied to the gate electrodes of the transistors 222-2 a and 222-2 bfrom being propagated to the transistors' 222-1 a and 222-1 b sidesthrough a connection point of the drain sides of the transistors 222-2 aand 222-2 b, as noise. Accordingly, the imaging element 11 that includesthe comparator 52A can capture a good image with lower noise.

FIG. 20 illustrates a second modification example of a circuitconfiguration of the comparator 52.

In a comparator 52B illustrated in FIG. 20 , the same symbols orreference numerals are attached to the same configurations as those ofthe comparator 52 of FIG. 17 , and detailed description thereof will beomitted. That is, the comparator 52B is the same as the comparator 52 ofFIG. 17 in that the comparator 52B includes the second amplificationunit 202 and the third amplification unit 203 and a differential paircircuit 201B includes transistors 211 to 213. In addition, thecomparator 52B has the same configuration as that of the comparator 52of FIG. 17 , in that a first differential pair unit 214 a-B and a seconddifferential pair unit 214 b-B are provided in parallel with each other.

Meanwhile, in the comparator 52B, disposal of the transistors that areused for switching the active state and the standby state of the firstdifferential pair unit 214 a-B and the second differential pair unit 214b-B is different from that of the comparator 52 of FIG. 17 .

That is, in the first differential pair unit 214 a-B of the comparator52B, in the same manner as in the comparator 52 of FIG. 17 , a pair ofthe transistors 224-1 a and 224-2 a that is used for switching theactive state and the standby state are respectively disposed on thesource sides of a pair of the transistors 222-1 a and 222-2 a that isused for comparing signals. In addition to this, the first differentialpair unit 214 a-B of the comparator 52B has a configuration in which apair of the transistors 225-1 a and 225-2 a that is used for switchingthe active state and the standby state are respectively disposed on thedrain sides of a pair of the transistors 222-1 a and 222-2 a that isused for comparing signals.

That is, the first differential pair unit 214 a-B of the comparator 52Bhas a configuration in which a pair of the transistors 224-1 a and 224-2a and a pair of the transistors 225-1 a and 225-2 a are respectivelydisposed on both the source sides and the drain sides of a pair of thetransistors 222-1 a and 222-2 a.

In the same manner, the second differential pair unit 214 b-B of thecomparator 52B has a configuration in which a pair of the transistors224-1 b and 224-2 b and a pair of the transistors 225-1 b and 225-2 bare respectively disposed on both the source sides and the drain sidesof a pair of the transistors 222-1 b and 222-2 b.

The comparator 52B is configured in this way, and can perform the drivedescribed above with reference to FIG. 18 , in the same manner as in thecomparator 52 of FIG. 17 .

Then, for example, the comparator 52B can prevent the ramp signal thatis applied to the gate electrodes of the transistors 222-2 a and 222-2 bfrom being propagated to the transistors 222-1 a and 222-1 b sidesthrough the connection point of the drain sides of the transistors 222-2a and 222-2 b, as noise. In addition, since a load of the differentialpair unit (any one of the first differential pair unit 214 a-B and thesecond differential pair unit 214 b-B) in the standby state is not seenas a differential pair output, the comparator 52B can avoid a decreaseof the speed caused by a load increase. Accordingly, the image element11 including the comparator 52B can capture a good image with lowernoise at a high speed.

FIG. 21 illustrates a third modification example of a circuitconfiguration of the comparator 52.

In a comparator 52C illustrated in FIG. 21 , the same symbols orreference numerals are attached to the same configurations as those ofthe comparator 52 of FIG. 17 , and a detailed description thereof willbe omitted. That is, the comparator 52C is the same as the comparator 52of FIG. 17 in that the comparator 52C includes the second amplificationunit 202 and the third amplification unit 203 and a differential paircircuit 201C includes transistors 211 to 213. In addition, thecomparator 52C has the same configuration as that of the comparator 52of FIG. 17 , in that a first differential pair unit 214 a-C and a seconddifferential pair unit 214 b-C are provided in parallel with each other.

Meanwhile, in the comparator 52C, a connection configuration of a pairof transistors 223-1 a and 223-2 a for performing an auto-zero operationis different from that of the comparator 52 of FIG. 17 .

That is, in the first differential pair unit 214 a of the comparator 52of FIG. 17 , a pair of transistors 223-1 a and 223-2 a for performing anauto-zero operation is respectively disposed, so as to connect betweenthe gate electrodes of a pair of the transistors 222-1 a and 222-2 athat is used for comparing signals and a connection point of each of apair of transistors 221-1 a and 221-2 a, and a pair of the capacitors222-1 a and 222-2 a that is used for comparing signals and connectionpoints of a pair of transistors 224-1 a and 224-2 a that is used forswitching the active state and the standby state. In addition, in thesecond differential pair unit 214 b of the comparator 52 of FIG. 17 , apair of transistors 223-1 b and 223-2 b for performing the auto-zerooperation is respectively disposed, so as to connect between the gateelectrodes of a pair of the transistors 222-1 b and 222-2 b that is usedfor comparing the signals and connection points of each of a pair oftransistors 221-1 b and 221-2 b, and a pair of the capacitors 222-1 band 222-2 b that is used for comparing signals and a connection point ofa pair of transistors 224-1 b and 224-2 b that is used for switching theactive state and the standby state.

In contrast to this, in the first differential pair unit 214 a-C of thecomparator 52C, a pair of transistors 223-1 a and 223-2 a for performingan auto-zero operation is respectively disposed, so as to connectbetween the gate electrodes of a pair of the transistors 222-1 a and222-2 a that is used for comparing the signals and connection points ofeach of a pair of capacitors 221-1 a and 221-2 a, and source sides of apair of transistors 224-1 a and 224-2 a that is used for switching theactive state and the standby state.

In the same manner, in the second differential pair unit 214 b-C of thecomparator 52C, a pair of transistors 223-1 a and 223-2 a for performingan auto-zero operation are respectively disposed, so as to connectbetween the gate electrodes of a pair of the transistors 222-1 b and222-2 b that is used for comparing the signals and connection points ofeach of a pair of capacitors 221-1 b and 221-2 b, and source sides of apair of transistors 224-1 b and 224-2 b that is used for switching theactive state and the standby state.

The comparator 52C that is configured in this way includes a pair oftransistors 224-1 a and 224-2 a, and a pair of transistors 224-1 b and224-2 b, and thereby can perform the auto-zero operation and to aligndifferences between voltage thresholds of the transistors.

FIG. 22 illustrates a fourth modification example of a circuitconfiguration of the comparator 52.

In a comparator 52D illustrated in FIG. 22 , the same symbols orreference numerals are attached to the same configurations as those ofthe comparator 52 of FIG. 17 , and a detailed description thereof willbe omitted. That is, the comparator 52D is the same as the comparator 52of FIG. 17 in that the comparator 52D includes the second amplificationunit 202 and the third amplification unit 203 and a differential paircircuit 201D, which includes transistors 211 to 213. In addition, thecomparator 52D has the same configuration as that of the comparator 52of FIG. 17 , in that a first differential pair unit 214 a-D and a seconddifferential pair unit 214 b-D are provided in parallel with each other.

Meanwhile, the comparator 52D has a different configuration from thecomparator 52 of FIG. 17 in that a circuit configuration, on a side,which is connected to the ramp signal generation circuit 17, and towhich the ramp signal is supplied, is commonly used with the firstdifferential pair unit 214 a-D and the second differential pair unit 214b-D. That is, the comparator 52D is configured in such a manner that thecircuit configuration, which is configured with a capacitor 221, atransistor 222, and a transistor 223, on the ramp signal side iscommonly used with the first differential pair unit 214 a-D and thesecond differential pair unit 214 b-D.

That is, the first differential pair unit 214 a-D performs a comparisonoperation of the pixel signal and the ramp signal, using a circuitconfiguration, which is configured with a capacitor 221-1 a, atransistor 222-1 a, and a transistor 223-1 a, on the pixel signal side,and using the circuit configuration, which is configured with thecapacitor 221, the transistor 222, and the transistor 223, on the rampsignal side. In the same manner, the second differential pair unit 214b-D performs the comparison operation of the pixel signal and the rampsignal, using a circuit configuration, which is configured with acapacitor 221-1 b, a transistor 222-1 b, and a transistor 223-1 b, onthe pixel signal side, and using the circuit configuration, which isconfigured with the capacitor 221, the transistor 222, and thetransistor 223, on the ramp signal side.

Then, the transistor 224-1 a that is connected to the circuitconfiguration on the pixel signal side of the first differential pairunit 214 a-D, and the transistor 224-1 b that is connected to thecircuit configuration on the pixel signal side of the seconddifferential pair unit 214 b-D, are used for switching the active stateand the standby state.

In the comparator 52D configured in this way, the circuit configurationon the ramp signal side is shared with the first differential pair unit214 a-D and the second differential pair unit 214 b-D, and thus it ispossible to configure the comparator 52D with a small area, for example,compared to the comparator 52 of FIG. 17 . Accordingly, it is possibleto perform miniaturization of the entire imaging element 11.

Next, the drive signals and the pixel signals of the imaging element 11will be described with reference to FIG. 23 .

FIG. 23 illustrates a timing chart of one horizontal period (1H) whenthe pixel signals are read in the order of a pixel 21 a-1, a pixel 21b-1, a pixel 21 a-2, and a pixel 21 b-2, that are disposed asillustrated in FIG. 24 .

A selection signal SEL1 that is supplied to the pixel 21 a-1 and thepixel 21 a-2, which are connected to the first vertical signal line 23a, a reset signal RST1, transfer signals TG1 and TG2, a selection signalSEL2 that is supplied to the pixel 21 b-1 and the pixel 21 b-2 which areconnected to the second vertical signal line 23 b, a reset signal RST3,transfer signals TG3 and TG4, a pixel signal VSL1 that is output throughthe first vertical signal line 23 a, a pixel signal VSL2 that is outputthrough the second vertical signal line 23 b, and a ramp signal Rampthat is output from the ramp signal generation circuit 17, aresequentially illustrated from a top side of FIG. 23 .

To begin with, the pixel 21 a-1 and the pixel 21 b-1 are driven, a Pphase (pixel signal with reset level) of the pixel 21 a-1 is read, andthereafter a P phase of the pixel 21 b-1 is read. After that, a D phase(pixel signal with signal level) of the pixel 21 a-1 is read, andthereafter a D phase of the pixel 21 b-1 is read. Subsequently, thepixel 21 a-2 and the pixel 21 b-2 are driven, a P phase of the pixel 21a-2 is read, and thereafter a P phase of the pixel 21 b-2 is read. Afterthat, a D phase of the pixel 21 a-2 is read, and thereafter a D phase ofthe pixel 21 b-2 is read.

Hereinafter, with regard to the pixel 21 a-1 and the pixel 21 b-1, thepixel 21 a-1 from which the pixel signal is first read is referred to asprimary, and the pixel 21 b-1 from which the pixel signal issubsequently read is referred to as secondary. In the same manner, thepixel 21 a-2 is referred to as primary, and the pixel 21 b-2 is referredto as secondary.

In the imaging element 11 that is driven according to the timing chart,if, during a reading operation of one of the pixel 21 a and the pixel 21b, a shutter operation of the other is ended, a power supply load ischanged. For this reason, noise of a lateral belt shape, which isreferred to as a shutter step, can occur between the row in which thereading operation and the shutter operation are simultaneously performedand the row in which only a reading operation is performed.

Thus, in the imaging element 11, in order to avoid such a change of thepower supply load, a dummy read row may be provided. The reading of thepixel signal is not performed in the dummy read row, and it is possiblefor the dummy read row to employ a dummy read control that supplies areset pulse and a transfer pulse.

The dummy read control will be described with reference to FIG. 25 andFIG. 26 .

FIG. 25 illustrates a timing chart when a control that suppresses thechange of the power supply load caused by a transfer signal in the dummyread row is performed.

The ramp signal Ramp that is output from the ramp signal generationcircuit 17, the transfer signal of primary and the transfer signal ofsecondary, which perform reading of the pixel signal, in an opening row,the transfer signal of the primary and the transfer signal of thesecondary in the dummy read row, a negative potential change when thedummy read control is not performed, and a negative potential changewhen the dummy read control is performed, are sequentially illustratedfrom a top side of FIG. 25 . The negative potential change relates to apower supply that is connected to the second vertical signal line 23 b.

As illustrated in FIG. 25 , when the dummy read control is performed, acontrol is performed, which generates a pulse in the transfer signal ofthe secondary in the dummy read row, so as to coincide with the timingin which a pulse of the transfer signal of the secondary in the openingrow is generated. In addition, in a timing in which a D phase of theprimary is ended, a control is performed, which generates a pulse in thetransfer signal of the primary in the dummy read row.

By performing such a dummy read control, it is possible to adjust thenegative potential change of the power supply that is connected to thesecond vertical signal line 23 b, using the P phase and D phase in theprimary row and the P phase and the D phase in the secondary row.Accordingly, the imaging element 11 can avoid the noise of a lateralbelt shape that is referred to as a shutter step described above.

FIG. 26 illustrates a timing chart when a control that suppresses thechange of the power supply load caused by the reset signal in the dummyread row is performed.

The ramp signal Ramp that is output from the ramp signal generationcircuit 17, a selection signal of the primary and a selection signal ofthe secondary in the opening row in which the read of the pixel signalis performed, a reset signal of the primary and a reset signal of thesecondary in the opening row in which the read of the pixel signal isperformed, a selection signal of the primary and a selection signal ofthe secondary in the dummy read row, and a reset signal of the primaryand a reset signal of the secondary in the dummy read row, aresequentially illustrated from a top side of FIG. 26 .

As illustrated in FIG. 26 , in the reset signal of the primary in thedummy read row, the dummy read control that generates a pulse forperforming the dummy read operation is performed between the P phase ofthe primary and the P phase of the secondary.

By performing the dummy read control, it is possible to adjust thenegative potential change of the power supply that is connected to thesecond vertical signal line 23 b, using the P phase and the D phase inthe primary row, and the P phase and the D phase in the secondary row.Accordingly, the imaging element 11 can avoid the noise of a lateralbelt shape that is referred to as a shutter step described above.

As described above, the dummy read row in which the read of the pixelsignal is not performed is provided, the dummy read control thatsuppresses the negative potential change is performed by the pixel 21 athat is the primary and the pixel 21 b that is the secondary, and thusthe imaging element 11 can suppress an occurrence of noise and cancapture an image with a higher image quality.

However, in the imaging element 11, when a negative potential is used asan OFF potential of the transfer transistor 32 or the selectiontransistor 35, a generation or the like of the negative potential changecaused by the shutter operation, or a potential change from the verticalsignal line 23 can affect the read signal (i.e., signal that is readfrom the pixel 21).

Therefore, in order to avoid a negative influence caused by thegeneration or the like of the negative potential change caused by theshutter operation, or the potential change from the vertical signal line23, the imaging element 11 can employ a configuration in which thenegative potentials are separated into two systems for reading andshuttering.

Next, the imaging element 11 that is configured to separate the negativepotential into systems will be described with reference to FIG. 27 toFIG. 29 .

FIG. 27 illustrates a portion of the pixel area 12 and the verticaldrive circuit 13 in the imaging element 11.

The pixels 21 of four columns by sixteen rows among the plurality ofpixels 21 disposed in a matrix are included in the pixel area 12illustrated in FIG. 27 , and the pixels 21 employ the pixel-sharingstructure described above with reference to FIG. 6 . That is, in thesharing pixel 303 of FIG. 27 , the pixel-sharing structure is configuredby eight pixels 21 of two columns by four rows, and the eight sharingpixels 303 are disposed by two columns by four rows. Here, the sharingpixel 303 a-1 and the sharing pixel 303 a-2 are the primary, and thesharing pixel 303 b-1 and the sharing pixel 303 b-2 are the secondary.

In addition, in the vertical drive circuit 13, four four-row drive units302 are provided in correspondence to the sharing pixels 303 that aredisposed by four rows, in the sixteen-row drive unit 301 for driving thepixels 21 in the sixteen rows.

The four-row drive unit 302 a-1 supplies a drive signal to the sharingpixel 303 a-1, the four-row drive unit 302 a-2 supplies a drive signalto the sharing pixel 303 a-2, the four-row drive unit 302 b-1 supplies adrive signal to the sharing pixel 303 b-1, and the four-row drive unit302 b-2 supplies a drive signal to the sharing pixel 303 b-2.

At this time, the vertical drive circuit 13 is configured in such amanner that the negative potentials being used are separated by thefour-row drive unit 302 a-1 that drives the sharing pixel 303 a-1, thefour-row drive unit 302 a-2 that drives the sharing pixel 303 a-2, thefour-row drive unit 302 b-1 that drives the sharing pixel 303 b-1, andthe four-row drive unit 302 b-2 that drives the sharing pixel 303 b-2.

In this way, by separating the negative potential using the primary andthe secondary, it is possible to prevent the generation or the like ofthe negative potential change caused by the shutter operation, or thepotential change from the vertical signal line 23 from affecting theread signal.

Here, a system separation of the negative potential of the related artwill be described with reference to FIG. 28 .

As illustrated in FIG. 28 , a transfer signal supply unit 311 that isconnected to the pixel 21 is configured to include a pair of transistor321-1 and 321-2, and an amplifier 322. Then, a pulse that becomes atransfer signal is inverted by an inversion amplification unit 312, theinverted signal is supplied to the transistor 321-1, and the pulse thatbecomes the transfer signal is supplied to the transistor 321-2 withoutbeing inverted. In addition, the transistor 321-1 is grounded through acapacitor 314-1, and a charge pump 313-1 is connected to a connectionpoint VRL1 of the transistor 321-1 and the capacitor 314-1. In the samemanner, the transistor 321-2 is grounded through a capacitor 314-2, anda charge pump 313-2 is connected to a connection point VRL2 of thetransistor 321-2 and the capacitor 314-2.

The transfer signal supply unit 311 switches the charge pump 313-1 andthe charge pump 313-2 in a read state and a settling state according tothe pulse, and thus is configured to separate a negative potential foreach state.

In this way, in the related art, the negative potential is separated inthe read state and the settling state of one pixel 21. The separation ofthe negative potential is not considered between the pixel 21 a that isthe primary and the pixel 21 b that is the secondary.

In contrast to this, the system separation of the negative potential ofthe imaging element 11 will be described with reference to FIG. 29 .

As illustrated in FIG. 29 , in the imaging element 11, the systemseparation of the negative potential is not performed in the pixel 21 athat is the primary and the pixel 21 b that is the secondary.

That is, the transfer signal supply unit 311 is configured to include anamplifier 322 a that supplies the transfer signal to the pixel 21 a, andan amplifier 322 b that supplies the transfer signal to the pixel 21 b.Then, the amplifier 322 a is grounded through the capacitor 314 a, andthe charge pump 313 a is connected to a connection point VRL2 of theamplifier 322 a and the capacitor 314 a. In the same manner, theamplifier 322 b is grounded through the capacitor 314 b, and the chargepump 313 b is connected to a connection point VRL1 of the amplifier 322b and the capacitor 314 b.

In this way, the imaging element 11 is configured to separate thenegative potential in the pixel 21 a that is the primary and the pixel21 b that is the secondary. Accordingly, a generation of noise can besuppressed between the pixel 21 a and the pixel 21 b. Thus, the imagingelement 11 can prevent the noise from affecting the pixel, and tocapture an image with a higher image quality.

In the present embodiment, a configuration example in which two of thefirst vertical signal line 23 a and the second vertical signal line 23 bare provided in one column of the pixels 21 that are disposed in amatrix in the pixel area 12, is used, but a configuration in which aplurality of vertical signal lines 23 that are two or more is providedmay be used. For example, in the example of FIG. 3 , approximately thesame time is necessary for the settling and the hold of the pixelsignal, but for example, if the AD conversion processing itself can bespeeded up and the time for holding an output of the pixel signal can bereduced, while a plurality of pixels performs the settling of the pixelsignals, the AD conversion of the pixel signals that are output fromanother plurality of pixels can be sequentially performed. Accordingly,it is possible to further speed up the entire AD conversion.

Furthermore, the imaging element 11 can be applied to both a surfaceradiation type CMOS image sensor in which light is radiated onto asurface, on which a wiring layer is laminated, of a semiconductorsubstrate in which the pixels 21 are formed, and a backsideradiation-type CMOS image sensor in which light is radiated into abackside opposite to the surface. In addition, the image element 11 canbe applied to a stack-type CMOS image sensor, which is configured bystacking a sensor substrate in which the pixels 21 are formed on acircuit substrate in which a control circuit 18 (FIG. 1 ) or the like isformed. In addition, as described above, processing of reading the pixelsignal and performing the AD conversion of the read signal can berealized by executing a program by the control circuit 18.

The imaging element 11, according to each embodiment described above,can be applied to various electronic apparatuses, such as an imagingsystem (e.g., a digital still camera or a digital video camera, a mobilephone with an imaging function, or other apparatuses with an imagingfunction).

FIG. 30 is a block diagram illustrating a configuration example of animaging device, which is mounted in an electronic apparatus.

As illustrated in FIG. 30 , an imaging device 401 is configured toinclude an optical system 402, an imaging element 403, a signalprocessing circuit 404, a monitor 405, and a memory 406, and can image astill image and a moving image.

The optical system 402 is configured to include one or a plurality oflenses, leads image light (i.e., incident light) from a subject to theimaging element 403, and image formation is made to a light-receivingsurface (i.e., sensor portion) of the imaging element 403.

The imaging element 11 according to each embodiment described above isapplied as the imaging element 403. Electrons are stored in the imagingelement 403 for a predetermined period, according to an image that isformed in the light-receiving surface through the optical system 402.Then, a signal according to the electrons that are stored in the imagingelement 403 is supplied to the signal processing circuit 404.

The signal processing circuit 404 performs various signal processingwith respect to the pixel signal that is output from the imaging element403. An image (i.e., image data) that is obtained by performing thesignal processing by the signal processing circuit 404 is supplied tothe monitor 405 to be displayed, and is supplied to the memory 406 andstored (recorded) there.

The imaging device 401 configured in this way can apply the imagingelement 11 according to each embodiment described above, therebyspeeding up the AD conversion processing, and thus it is possible tocapture an image with a higher frame rate, for example.

FIG. 31 is a view illustrating a usage example in which theabove-described image sensor (i.e., imaging element 11) is used.

The above-described image sensor can be used for various cases in whichlight, such as visible light, infrared light, ultraviolet light, orX-rays is sensed, as follows.

An image capturing device that is provided for appreciation, such as adigital camera or a portable device with a camera function.

A device that is provided for traffic, such as an in-vehicle sensor thatcaptures the front, the rear, the surrounding, the inside, or the likeof a vehicle, a monitoring camera that monitors a travelling vehicle ora road, or a distance-measuring sensor that performs a distancemeasurement, such as inter-vehicles, for safe driving, such as anautomatic stop, recognition of a state of a driver, or the like.

A device that is provided to a home appliance, such as a TV, arefrigerator, or an air conditioner, in order to capture a gesture of auser, and to perform an apparatus operation according to the gesture.

A device that is provided for medical care or health care, such as anendoscope or a device that performs angiography by receiving infraredlight.

A device that is provided for security, such as a monitoring camera forsecurity or a camera for person authentication.

A device that is provided for cosmetics, such as a skin measuring devicethat captures skin or a microscope that captures scalp.

A device that is provided for sports, such as an action camera or awearable camera for sports.

A device that is provided for agriculture, such as a camera formonitoring a status of a field or crops.

Further, for example, the present technology can have the followingconfigurations.

-   -   (1)

An imaging device comprising:

-   -   a pixel array including a plurality of pixels two-dimensionally        arranged in a matrix pattern;    -   a plurality of column signal lines disposed according to a first        column of the pixels, wherein at least one column signal line of        the plurality of column signal lines is connected to two or more        pixels in the first column; and    -   an analog to digital converter shared by the plurality of column        signal lines.    -   (2)

The imaging device according to (2), wherein the plurality of columnsignal lines disposed according to the first column are parallel to eachother.

-   -   (3)

The imaging device according to any one of (2) to (3), furthercomprising: a first column signal line of the plurality of column signallines; and a second column signal line of the plurality of column signallines, wherein pixels in even numbered rows share the first columnsignal line and pixels in odd numbered rows share the second columnsignal line.

-   -   (4)

The imaging device according to any one of (1) to (3), wherein one ormore of the plurality of column signal lines are selectively coupled toa same comparator.

-   -   (5)

The solid-state image pickup device according to (4), further comprisinga switch for each of the plurality of column signal lines, wherein eachswitch is coupled to a first terminal of the comparator.

-   -   (6)

The imaging device according to (5), further comprising: a ramp signalgeneration circuit connected to a second terminal of the comparator; anda counter unit connected to an output terminal of the comparator,wherein the counter unit is coupled to a data output signal line.

-   -   (7)

The imaging device according to any one of (5) to (6), wherein thecomparator includes: a first differential pair unit connected to a firstcolumn signal line of the plurality of column signal lines; and a seconddifferential pair unit connected to a second column signal line of theplurality of column signal lines.

-   -   (8)

The imaging device according to (7), wherein the first differential pairunit and the second differential pair unit are connected to a rampsignal node provided from a ramp signal generation circuit.

-   -   (9)

The imaging device according to (8), wherein when the first differentialpair unit is active, the second differential pair unit is inactive, andwherein when the first differential pair unit is inactive, the seconddifferential pair unit is active.

-   -   (10)

The imaging device according to (9), wherein pixels in even numberedrows share the first column signal line and pixels in odd numbered rowsshare the second column signal line.

-   -   (11)

The imaging device according to any one of (7) to (10), wherein anoutput from at least one of the first differential pair unit and thesecond differential pair unit is provided to at least one of a firstamplification unit and a second amplification unit.

-   -   (12)

The imaging device according to any one of (7) to (11), wherein thefirst differential pair unit includes two transistors connected to afirst auto-zero connection node, and the second differential pair unitincludes two transistors connected to a second auto-zero connectionnode.

-   -   (13)

The imaging device according to any one of (7) to (12), wherein thefirst differential pair unit includes a transistor connected to a firstauto-zero connection node, the second differential pair unit includes atransistor connected to a second auto-zero connection node, and thefirst differential pair unit and the second differential pair unit sharea transistor connected to a third auto-zero connection node.

-   -   (14)

The imaging device according to any one of (4) to (6), furthercomprising: a switch for each of the plurality of column signal lines;and a capacitor for each of the plurality of column signal lines,wherein a first terminal of the capacitor is connected to the switch anda second terminal of the capacitor is connected to a first terminal ofthe comparator.

-   -   (15)

The imaging device according to any one of (1) to (14), furthercomprising: a first pixel sharing structure including at least twopixels in adjacent columns and at least two pixels in adjacent rows; asecond pixel sharing structure including at least two pixels in adjacentcolumns and at least two pixels in adjacent rows, wherein the firstpixel sharing structure and the second pixel sharing structure arearranged in a same column, wherein the first pixel sharing structure isconnected to a first column signal line of the plurality of columnsignal lines, and wherein the second pixel sharing structure isconnected to a second column signal line of the plurality of columnsignal lines.

-   -   (16)

The imaging device according to (16), further comprising color filtersdisposed on the at least two pixels in adjacent columns and the at leasttwo pixels in adjacent rows, wherein the color filters are arrangedaccording to a Bayer pattern.

-   -   (17)

The imaging device according to any one of (1) to (16), wherein areading of a reset signal associated with a second signal column line ofthe plurality of signal column lines occurs between a reading of a resetsignal associated with a first signal column line of the plurality ofsignal column lines and a reading of a signal corresponding to an amountof light received by a photodiode connected to the first column signalline.

-   -   (18)

An electronic apparatus comprising:

-   -   an optical system including at least one lens; and    -   an imaging element configured to receive light through the        optical system, wherein the imaging element includes:    -   a pixel array including pixels two-dimensionally arranged in a        matrix pattern;    -   a plurality of column signal lines disposed according to a first        column of the pixels, wherein at least one column signal line of        the plurality of column signal lines is connected to two or more        pixels in the first column; and    -   an analog to digital converter shared by the plurality of column        signal lines.    -   (19)

A comparator comprising a differential pair circuit including:

-   -   a first differential pair unit connected to a first column        signal line of an imaging device; and    -   a second differential pair unit connected to a second column        signal line of the imaging device, wherein the first column        signal line and the second column signal line are for the same        column of pixel array units in a pixel array.    -   (20)

The comparator according to (19), wherein the first differential pairunit and the second differential pair unit are connected to a rampsignal provided from a ramp signal generation circuit.

-   -   (21)

The comparator according to any one of (19) to (20), wherein when thefirst differential pair unit is active, the second differential pairunit is inactive, and wherein when the first differential pair unit isinactive, the second differential pair unit is active.

-   -   (22)

The comparator according to any one of (19) to (21), wherein pixel unitsin even numbered rows share the first column signal line and pixel unitsin odd numbered rows share the second column signal line.

-   -   (23)

The comparator according to any one of (19) to (22), further comprising:a first amplification unit; and a second amplification unit, wherein anoutput from at least one of the first differential pair unit and thesecond differential pair unit is provided to the first amplificationunit and the second amplification unit.

-   -   (24)

The comparator according to any one of (19) to (23), wherein the firstdifferential pair unit includes two transistors connected to a firstauto-zero connection node, and the second differential pair unitincludes two transistors connected to a second auto-zero connectionnode.

-   -   (25)

The comparator according to any one of (19) to (23), wherein the firstdifferential pair unit includes a transistor connected to a firstauto-zero connection node, the second differential pair unit includes atransistor connected to a second auto-zero connection node, and thefirst differential pair unit and the second differential pair unit sharea transistor connected to a third auto-zero connection node.

-   -   (26)

An imaging element including: a pixel area in which a plurality ofpixels is disposed in a matrix; and a column AD signal processing unitin which an AD conversion unit that performs an AD (Analog to Digital)conversion of a pixel signal which is output from the pixel is providedin each column of the pixels, and the plurality of pixels that isdisposed in the same column is connected to the AD conversion unitthrough a predetermined number of vertical signal lines, in which thepixel connected through a portion of a predetermined number of thevertical signal lines performs a reset operation or a signal transferoperation, and concurrently, the AD conversion unit performs anoperation of an AD conversion of a pixel signal that is output from thepixel connected through the other vertical signal lines, and theoperations are alternately repeated.

-   -   (27)

The imaging element described in (26), in which for each sharing pixelthat shares a portion of the pixel in the plurality of pixels, the resetoperation or the signal transfer operation, and the AD conversion arealternately and concurrently performed in the pixel that each of thesharing pixels includes.

-   -   (28)

The imaging element described in (26) or (27), in which a predeterminednumber of capacitors is respectively provided between a predeterminednumber of the vertical signal lines and an input terminal of the ADconversion unit, and a switch connects the capacitors to an outputterminal of the AD conversion unit.

-   -   (29)

The imaging element described in (26) to (28), in which the two columnAD signal processing units are provided on an upper side and a lowerside in a column direction of the pixel area, respectively.

-   -   (30)

The imaging element described in (26) to (29), in which the ADconversion unit is provided in each one column of the pixel, and theplurality of pixels disposed in the one column is connected to the ADconversion unit through a first vertical signal line or a secondvertical signal line, in which a reset operation period of the pixelconnected to the first vertical signal line is concurrent with an ADconversion period in which an AD conversion of a pixel signal with asignal level that is output from the pixel connected to the secondvertical signal line is performed, in which an AD conversion period inwhich an AD conversion of a pixel signal with a reset level that isoutput from the pixel connected to the first vertical signal line isconcurrent with a reset operation period of the pixel connected to thesecond vertical signal line, in which a signal transfer period of thepixel connected to the first vertical signal line is concurrent with anAD conversion period in which an AD conversion of a pixel signal with areset level that is output from the pixel connected to the secondvertical signal line is performed, and in which an AD conversion periodin which an AD conversion of a pixel signal with a signal level isperformed in the pixel connected to the first vertical signal line isconcurrent with a signal transfer period of the pixel connected to thesecond vertical signal line.

-   -   (31)

The imaging element described in (30), in which the AD conversion unitincludes a retention unit that retains a value that is obtained byperforming the AD conversion of the pixel signal, in which the ADconversion unit retains a value that is obtained by performing the ADconversion of the pixel signal with a signal level that is output fromthe pixel connected to the second vertical signal line, performs the ADconversion of the pixel signal with a reset level that is output fromthe pixel connected to the second vertical signal line, and thereafteroutputs a difference between the values, and in which the AD conversionunit retains a value that is obtained by performing the AD conversion ofthe pixel signal with a reset level that is output from the pixelconnected to the first vertical signal line, performs the AD conversionof the pixel signal with a signal level that is output from the pixelconnected to the first vertical signal line, and thereafter outputs adifference between the values.

-   -   (32)

The imaging element described in (26) to (31), in which in a metal layeron which a predetermined number of the vertical signal lines are formed,an inter-signal-line shield that is fixed to a predetermined potentialis formed between the vertical signal lines.

-   -   (33)

The imaging element described in (32), in which in a connection sectionof the predetermined pixel and a predetermined vertical signal line usedfor reading a pixel signal from the pixel, a shield structure isprovided which shields the predetermined vertical signal line withrespect to the other vertical signal lines that are not used for readingthe pixel signal from the predetermined pixel.

-   -   (34)

The imaging element described in (33), in which the shield structure isconfigured using at least two metal layers provided between a metallayer in which the vertical signal line and the inter-signal-line shieldare formed, and a semiconductor substrate, and the metal layer on anupper side disposed between the metal layer on a lower side that isconnected to the predetermined vertical signal line, and the othervertical signal lines is connected to the inter-signal-line shield.

-   -   (35)

The imaging element described in (26) to (34), in which in a comparatorincluded in the AD conversion unit, differential pair units, each ofwhich receives a pixel signal that is output from the pixel and a rampsignal, and compares the two signals so as to perform an AD conversionof the pixel signal, are provided in parallel with each other in apredetermined number of each vertical signal lines, and in whichswitching units, each switching an active state in which the pixelsignal is compared with the ramp signal, and a standby state in whichthe pixel signal is not compared with the ramp signal, are provided ineach differential pair unit.

-   -   (36)

The imaging element described in (35), in which the switching units aredisposed on source sides of a pair of transistors, gate electrodes ofwhich the pixel signal and the ramp signal are respectively applied to.

-   -   (37)

The imaging element described in (35), in which the switching units aredisposed on drain sides of a pair of transistors, gate electrodes ofwhich the pixel signal and the ramp signal are respectively applied to.

-   -   (38)

The imaging element described in (35), in which the switching units aredisposed on both source sides and drain sides of a pair of transistors,gate electrodes of which the pixel signal and the ramp signal arerespectively applied to.

-   -   (39)

The imaging element described in (35), in which a pair of capacitorsthat respectively retain potentials according to levels of the pixelsignal and the ramp signal, and a pair of transistors for auto-zero forperforming an auto-zero operation of the differential pair unit, areprovided in each differential pair unit, and in which a pair of thetransistors for auto-zero is disposed so as to connect between eachconnection point of a pair of transistors for comparison, gateelectrodes of which the pixel signal and the ramp signal arerespectively applied to, and the capacitor, and each connection point ofthe transistors for comparison and the switching units.

-   -   (40)

The imaging element described in (35), in which a pair of capacitorsthat respectively retain potentials according to levels of the pixelsignal and the ramp signal, and a pair of transistors for performing anauto-zero operation of the differential pair unit, are provided in eachdifferential pair unit, in which the switching units are disposed onsources sides of a pair of transistor for comparison, gate electrodes ofwhich the pixel signal and the ramp signal are respectively applied to,and in which a pair of the transistors for auto-zero is disposed so asto connect between each connection point of the transistors forcomparison and the capacitor, and each source side of the switchingunits.

-   -   (41) The imaging element described in (35) to (40), in which in        a predetermined number of the differential pair units, a circuit        configuration on a side to which the ramp signal is input is        shared.    -   (42) The imaging element described in (26) to (41), in which a        dummy read row in which pixels in which reading of a pixel        signal is not performed are disposed is provided, and a control        is performed which suppresses a change of a negative potential        of the pixels that concurrently and alternately perform a reset        operation or a signal transfer operation and an AD conversion        operation.    -   (43) The imaging element described in (26) to (41), in which a        negative potential is configured so as to be separated for each        pixel that concurrently and alternately perform a reset        operation or a signal transfer operation and an AD conversion        operation.    -   (44) An imaging method of an imaging element that includes a        pixel area in which a plurality of pixels is disposed in a        matrix, and a column AD signal processing unit in which an AD        conversion unit that performs an AD (Analog to Digital)        conversion of a pixel signal which is output from the pixel is        provided in each column of the pixels, and the plurality of        pixels that is disposed in the same column is connected to the        AD conversion unit through a predetermined number of vertical        signal lines, the method including: performing a reset operation        or a signal transfer operation using the pixel connected through        a portion of a predetermined number of the vertical signal        lines, and concurrently, performing an operation of an AD        conversion of a pixel signal that is output from the pixel        connected through the other vertical signal lines using the AD        conversion unit, and the operations being alternately repeated.    -   (45) An electronic Apparatus including: an imaging element that        includes a pixel area in which a plurality of pixels is disposed        in a matrix, and a column AD signal processing unit in which an        AD conversion unit that performs an AD (Analog to Digital)        conversion of a pixel signal which is output from the pixel is        provided in each column of the pixels, and the plurality of        pixels that is disposed in the same column is connected to the        AD conversion unit through a predetermined number of vertical        signal lines, in which the pixel connected through a portion of        a predetermined number of the vertical signal lines performs a        reset operation or a signal transfer operation, and        concurrently, the AD conversion unit performs an operation of an        AD conversion of a pixel signal that is output from the pixel        connected through the other vertical signal lines, and the        operations are alternately repeated.

It should be understood by those skilled in the art that variousmodifications, combinations, sub-combinations, and alterations may occurdepending on design requirements and other factors insofar as they arewithin the scope of the appended claims or the equivalents thereof.

REFERENCE SIGNS LIST

-   -   11 Imaging device    -   12 Pixel area    -   13 Vertical drive circuit    -   14 Column signal processing circuit    -   15 Horizontal drive circuit    -   16 Output circuit    -   17 Ramp signal generation circuit    -   18 Control circuit    -   21 Pixel    -   22 Horizontal signal line    -   23 Vertical signal line    -   24 Data output signal line    -   31 PD    -   32 Transfer transistor    -   33 FD unit    -   34 Amplification transistor    -   35 Selection transistor    -   36 Reset transistor    -   41 Column processing unit    -   42 Constant current source    -   51 Input switch    -   52 Comparator    -   53 Counter    -   54 Output switch    -   55 Retention unit    -   61 Sharing pixel    -   71, 72 Capacitor    -   73 Feedback switch

What is claimed is:
 1. Alight detecting device, comprising: acomparator, including; current mirror transistors; a first differentialpair unit, the first differential pair unit including; a firsttransistor, a gate of the first transistor configured to receive a firstpixel signal; a second transistor; a first select transistor coupled toone of the current mirror transistors and the first transistor; and asecond select transistor coupled to another one of the current mirrortransistors; and a second differential pair unit, the seconddifferential pair unit including; a third transistor, a gate of thethird transistor configured to receive a second pixel signal; a fourthtransistor; a third select transistor coupled the one of the currentmirror transistors and the third transistor; and a fourth selecttransistor coupled the other one of the current mirror transistors andthe fourth transistor, wherein a gate of the second transistor and agate of the fourth transistor are configured to receive a referencesignal.
 2. The light detecting device according to claim 1, furthercomprising: a first capacitor; and a second capacitor, wherein the firstcapacitor is coupled to the gate of the second transistor, and whereinthe second capacitor is coupled to the gate of the fourth transistor. 3.The light detecting device according to claim 2, further comprising: areference signal line, wherein reference signal line is coupled to thefirst and second capacitors.
 4. The light detecting device according toclaim 3, further comprising: a ramp signal generation circuit, wherein areference signal is provided from the ramp signal generation circuit tothe first and second capacitors over the reference signal line.
 5. Thelight detecting device according to claim 1, further comprising: acurrent source, wherein the current source is coupled to the first andsecond transistors.
 6. The light detecting device according to claim 5,wherein the current source is further coupled to the third and fourthtransistors.
 7. The light detecting device according to claim 1, whereinthe first pixel signal is provided to the first transistor by a firstvertical signal line, and wherein the second pixel signal is provided tothe third transistor by a second vertical signal line.
 8. The lightdetecting device according to claim 1, wherein a differential pairoutput is provided to an amplification unit.
 9. The light detectingdevice according to claim 1, wherein the first differential pair unitand the second differential pair unit are provided in parallel. 10.Alight detecting device, comprising: a comparator, including; currentmirror transistors; a first transistor, a gate of the first transistorconfigured to receive a first pixel signal; a second transistor, a gateof the second transistor configured to receive a reference signal; afirst select transistor coupled to one of the current mirror transistorsand further coupled to the first transistor; a third transistor, a gateof the third transistor configured to receive a second pixel signal; anda third select transistor coupled the one of the current mirrortransistors and further coupled to the third transistor.
 11. The lightdetecting device according to claim 10, further comprising: a firstcapacitor; and a second capacitor, wherein the first pixel signal isinput via the first capacitor from a first vertical signal line, andwherein the second pixel signal is input via a second capacitor from asecond vertical signal line.
 12. The light detecting device according toclaim 11, wherein the first and second vertical signal lines correspondto a first pixel column.
 13. The light detecting device according toclaim 12, further comprising: a shield line, wherein the shield line isdisposed between the first and second vertical signal lines.
 14. Thelight detecting device according to claim 10, wherein a differentialpair output is provided to an amplification unit.